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PubMedDate not supplied

[Corneal thickness progression from the thinnest point to the limbus: study based on a normal and a keratoconus population to create reference values].

PURPOSE: To study the variation and progression of the pachymetric values from the thinnest point towards the limbus in normal and keratoconic corneas; to establish reference curves for this parameter. METHODS: One hundred eyes with normal corneas and twenty-five eyes with mild keratoconus (stages I and II - Krumeich) were analyzed using the Orbscan. Concentric circles were drawn on the thinnest point of the cornea with increasing radii from 1 to 7 mm. The average results of each circle were calculated and inserted in an Excel table in order to arrange a progression chart for each case starting on the thinnest point. The SPSS software was also used for statistical analysis. Student's t test was then used to compare the found values. RESULTS: The average values on the thinnest point in normal patients was 511.6 microm (standard deviation 30.6). The average values of the thinnest point in patients with keratoconus was 424.4 microm (standard deviation 56.57). Statistically significant different values were reported (p<0.01) for all circles, and for 6 and 7 mm radii p=0.01. CONCLUSION: There is a greater pachymetric variability in patients with keratoconus. Keratoconic corneas also have a faster progression of pachymetric values than healthy eyes. Pachymetric progression complements traditional single point evaluation of corneal thickness and must be considered for the screening at refractive candidates. This parameter may represent an indirect index of the biomechanics of corneal tissue but this hypothesis still needs further studies.

Corneal Topography↗

PubMed2006

Population reference values for plasma total homocysteine concentrations in US adults after the fortification of cereals with folic acid.

BACKGROUND: Folic acid fortification has resulted in a dramatic increase in folate intake in the United States. Folate intake is inversely associated with circulating total homocysteine (tHcy). Elevated tHcy is directly associated with cardiovascular disease risk. OBJECTIVE: The aim of this study was to present the distribution of plasma concentrations of tHcy in US adults by using data from nationally representative sample surveys conducted since folic acid fortification was implemented. DESIGN: Data from the National Health and Nutrition Examination Surveys from 1999-2001 and 2001-2002 were used to study tHcy distribution by age, sex, and race-ethnicity in 9196 persons. RESULTS: Plasma concentrations of tHcy were higher in men than in women and in older persons than in younger persons. In those aged 19-30, 31-50, and 51-70 y but not in those aged >70 y, men had significantly (P < 0.0001) higher mean plasma concentrations of tHcy than did women. A race-ethnicity difference in plasma tHcy existed only in persons aged >70 y. Non-Hispanic blacks aged >70 y had significantly (P < 0.05) higher tHcy concentrations than did non-Hispanic white or Mexican American or Hispanic subjects in the same age group. Age-adjusted plasma tHcy concentrations did not differ significantly between non-Hispanic white (8.39 micromol/L), non-Hispanic black (8.92 micromol/L), and Mexican American or Hispanic (8.12 micromol/L) subjects. The rate of increase in plasma tHcy was greater in non-Hispanic blacks aged >/=50 y than in persons of similar age but of other races-ethnicities. CONCLUSIONS: These plasma tHcy data reflect the effects of folic acid fortification. Sex, age, and race-ethnicity differences persist in plasma tHcy concentrations.

Adult↗

PubMed1989

[Recent advances in the clinical study of the renin system. Reference values and conditions of validity].

Plasma renin activity, angiotensinogen, active renin and aldosterone concentrations and, 1 hour after addition of trypsin 1 mg per ml of plasma at -4 degrees C, prorenin and total renin concentrations were measured in 49 normotensive volunteers. Renin activity and active renin concentration were correlated (n = 98, r = 0.902, p less than 0.01) and their ratio was not dependent on the angiotensinogen concentration. Prorenin accounted for 90 per cent of total renin and was 40 per cent higher in males than in females in both supine and upright positions (p = 0.02 and p = 0.01). The change in position markedly increased plasma renin activity as well as active renin and aldosterone concentrations and, to a lesser degree, prorenin concentration, thereby raising the active/total renin ratio. Plasma renin activity, active renin concentration and plasma aldosterone concentration were significantly and negatively correlated with age, but not with urinary sodium excretion. Plasma renin activity and active renin and angiotensinogen concentrations were also measured in 14 patients with high angiotensinogen concentration (pregnant women and oestrogen users) and in 14 patients with cirrhosis and subnormal angiotensinogen concentration. In these patients the ratio of plasma renin activity to active renin concentration was correlated with the angiotensinogen concentration (n = 28, r = 0.643, p less than 0.01). The slope of the regression line between renin activity and active renin concentration was significantly different in patients with cirrhosis and in healthy volunteers, the measurement of renin activity leading to a ten-fold underestimation of active renin concentration. In clinical investigations of the renin system, plasma samples should be handled at room temperature to avoid cryoactivation of prorenin. The determination of active renin concentration should be preferred to that of plasma renin activity because it is not influenced by physiological or pathological variations in angiotensinogen.

Adolescent↗

PubMedDate not supplied

Ulnar 14-cm and 7-cm antidromic sensory studies to the fifth digit: reference values derived from a large population of normal subjects.

The ulnar antidromic sensory conduction study to the fifth digit is commonly performed in clinical electrodiagnosis. Several authors have published normal ranges for this study, but these published reports have been limited by generally small sample sizes. The purpose of this article is to present a large database of normal ranges for this nerve study. After obtaining Institutional Review Board approval, 258 asymptomatic subjects were tested bilaterally with an ulnar antidromic sensory technique recording from the fifth digit. Stimulation was performed 7 cm and 14 cm proximal to the recording electrode. Onset latency, peak latency, onset-to-peak amplitude, peak-to-peak amplitude, area, duration, and rise time were recorded. Side-to-side and 14- to 7-cm comparisons were made. A repeated measures analysis of variance was performed to determine whether any of the subjects' demographic characteristics of age, race, gender, height, or body mass index (kg/m2) were associated with different results for the nerve conduction measures. Increasing age and body mass index were found to correlate with decreasing amplitude and area. No other correlations were noted between the results and the physical characteristics. Mean onset latency was 1.4 +/- 0.2 ms at 7-cm and 2.6 +/- 0.2 ms at 14-cm stimulation. Mean peak latency was 2.0 +/- 0.2 ms at 7-cm and 3.4 +/- 0.3 ms at 14-cm stimulation. Mean onset-to-peak amplitude was 32 +/- 20 microV at 7-cm and 33 +/- 17 microV at 14-cm stimulation. Mean negative-to-positive-peak amplitude was 55 +/- 36 microV at 7-cm and 50 +/- 32 microV at 14-cm stimulation. Mean side-to-side difference for onset latency was 0 +/- 0.2 ms. Additional data is presented in the study.

Adult↗

PubMed2000

Establishment of reference values for standard dose short synacthen test (250 microgram), low dose short synacthen test (1 microgram) and insulin tolerance test for assessment of the hypothalamo-pituitary-adrenal axis in normal subjects.

OBJECTIVE: To assess the integrity of the hypothalamo-pituitary-adrenal(HPA) axis, many authors have proposed the short synacthen test (ACTH1-24, Tetracosactrin) as a replacement for the insulin tolerance test (ITT). The aim of this study was to compare the plasma cortisol response obtained with both short synacthen tests (high dose (HDT, 250 microgram) and low dose (LDT, 1 microgram)) with the peak reached during the ITT in healthy volunteers, and to establish the plasma cortisol cut-off level in each test. SUBJECTS AND METHODS: Thirty healthy subjects (16 F, 14 M), mean age 34 years, underwent both short synacthen tests. Twenty healthy subjects, 15 of whom (11 F, nine M) belonged to the above group, mean age 30 years, underwent an ITT. Plasma cortisol was measured using a chemiluminiscence immunoassay. RESULTS: There were no differences between plasma cortisol 30 minutes after both short synacthen tests (HDT: 684 +/- 123, LDT: 669 +/- 119 nmol/l) and the peaks reached with the LDT (691 +/- 123 nmol/l) and the ITT (673 +/- 99 nmol/l). The only difference (P < 0.001) was found in the comparison of plasma cortisol peak reached with the HDT (802 +/- 142 nmol/l) with the other tests. Plasma cortisol levels obtained in the 5th percentile in each test were: at + 30 minutes: (HDT: 537, LDT: 489 nmol/l), peak: (HDT 649, LDT 498, ITT: 539 nmol/l). CONCLUSIONS: Comparison of the plasma cortisol response at + 30 minutes with both short ACTH tests and the peak in the insulin tolerance test did not reveal differences. Each test, for each time point and for each biochemical method, requires its own minimum threshold of normality to assess the hypothalamo-pituitary-adrenal axis.

Adult↗

PubMed2005

Continuous fetal heart rate monitoring during late gestation in cattle by means of Doppler ultrasonography: reference values obtained by computer-assisted analysis.

Continuous fetal heart rate (FHR) monitoring using transabdominal Doppler ultrasonography can be assumed to provide information about the viability of the bovine fetus during late gestation, as has been found in humans. To be able to recognize unfavourable fetal conditions, first the normal ranges of FHR parameters in cattle should be established. Therefore, in this study we aimed to determine the normal ranges of computerized FHR parameters, like basal fetal heart rate (BHR), number of accelerations and decelerations per hour and short and long term variation (STV and LTV) during the last 3 weeks before calving (n = 21 cows). Each cow had one recording in each of three episodes of 7 days before parturition. As recording time in the cow is limited, we also studied whether these FHR parameters differ between recordings of 30 and 60 min duration (n = 31 pairs of recordings). The outcomes of FHR recordings with a duration of 30 or 60 min did not differ significantly, except for a higher percentage of signal loss in the 60 min recordings. Therefore, determination of normal ranges was performed in 30 min recordings. BHR decreased from 3 to 2 weeks (114 to 109 bpm; P < 0.0001) before parturition and then remained constant until 2 days before calving. The mean number of accelerations per hour ranged between 4.4 and 5.0 h(-1) and did not change significantly with time. Compared to 3 weeks before parturition, STV was significantly higher at 2 weeks (P < 0.05), but not at 1 week before parturition (8.1, 10.0, and 9.2 ms, respectively). Changes in LTV showed a time course comparable to that of STV, but significance was not reached (51.4, 58.6, and 58.4 ms for respectively 3, 2 and 1 weeks before parturition). No decelerations were found during the period understudy. In conclusion, this study has provided normal ranges of bovine computerized FHR parameters during the last 3 weeks of gestation, allowing a comparison with data from cows with compromised gestations in future.

Animals↗

PubMed2004

The 24-h frequency-volume chart in adults reporting no voiding complaints: defining reference values and analysing variables.

OBJECTIVE: To determine the variables (e.g. voiding frequency, voided volumes, urine production) and their mutual relationships and differences between age groups and genders, using a frequency-volume chart (FVC) in an adult population (representing all age groups) who denied having any voiding complaints. SUBJECTS AND METHODS: In all, 1152 men and women aged > 20 years completed a 24-h FVC; registration started with the first voided volume in the morning and concluded with the first voided volume the next morning. The time of voiding and volume were both recorded, and bedtime hours noted. Each participant claimed to have no voiding complaints. The statistical analysis was aimed at discerning the relationships between the FVC variables, gender and age. RESULTS: There was a linear increase in mean 24-h voiding frequency and nocturia in men, from 6.0 and 0.5 in the third decade to 8.5 and 1.6 in those aged > 70 years. Contrary to men, in women the mean 24-h frequency declined slightly in the older decades; it increased from 6.9 in the third to 8.2 in the sixth, declining to 7.8 in those aged > 70 years. Nocturia in women increased linearly, although slower than in men, from 0.7 in the third decade to 1.4 in those aged > 70 years. The mean volume/void decreased significantly in both genders, from 313 to 209 mL in men, and from 274 to 240 mL in women. The mean 24-h volume was 1718 and 1762 mL in men and women, respectively. For both genders there was a strong linear association between 24-h urine production and voided volumes. CONCLUSION: The volume/void and maximum voided volume decreased significantly with age in both sexes, but more prominently in men. As a result, in men the frequency increased with age, probably reflecting subclinical changes associated with the development of prostatic enlargement. In contrast to men the frequency in women increased initially and decreased in the older groups. A higher 24-h urine production was associated with a higher mean volume/void.

Adult↗

PubMed2003

Sleep duration from infancy to adolescence: reference values and generational trends.

OBJECTIVE: The main purpose of the present study was to calculate percentile curves for total sleep duration per 24 hours, for nighttime and for daytime sleep duration from early infancy to late adolescence to illustrate the developmental course and age-specific variability of these variables among subjects. METHODS: A total of 493 subjects from the Zurich Longitudinal Studies were followed using structured sleep-related questionnaires at 1, 3, 6, 9, 12, 18, and 24 months after birth and then at annual intervals until 16 years of age. Gaussian percentiles for ages 3 months to 16 years were calculated for total sleep duration (time in bed) and nighttime and daytime sleep duration. The mean sleep duration for ages 1 to 16 years was estimated by generalized additive models based on the loess smoother; a cohort effect also had to be included. The standard deviation (SD) was estimated from the loess smoothed absolute residuals from the mean curve. For ages 3, 6, and 9 months, an alternative approach with a simple model linear in age was used. For age 1 month, empirical percentiles were calculated. RESULTS: Total sleep duration decreased from an average of 14.2 hours (SD: 1.9 hours) at 6 months of age to an average of 8.1 hours (SD: 0.8 hours) at 16 years of age. The variance showed the same declining trend: the interquartile range at 6 months after birth was 2.5 hours, whereas at 16 years of age, it was only 1.0 hours. Total sleep duration decreased across the studied cohorts (1974-1993) because of increasingly later bedtime but unchanged wake time across decades. Consolidation of nocturnal sleep occurred during the first 12 months after birth with a decreasing trend of daytime sleep. This resulted in a small increase of nighttime sleep duration by 1 year of age (mean 11.0 +/- 1.1 hours at 1 month to 11.7 +/- 1.0 hours at 1 year of age). The most prominent decline in napping habits occurred between 1.5 years of age (96.4% of all children) and 4 years of age (35.4%). CONCLUSIONS: Percentile curves provide valuable information on developmental course and age-specific variability of sleep duration for the health care professional who deals with sleep problems in pediatric practice.

Adolescent↗

PubMed2006

[Trabecular bone mineral density measured by quantitative CT of the lumbar spine in children and adolescents: reference values and peak bone mass].

PURPOSE: The aim of this study was to assess bone density values in the trabecular substance of the lumbar vertebral column in children and young adults in Germany from infancy to the age of peak bone mass. MATERIALS AND METHODS: We performed quantitative computed tomography (QCT) on the first lumbar vertebra in 28 children and adolescents without diseases that may influence bone metabolism (15 boys, 13 girls, mean ages 11 and 8 years, respectively). We also measured 17 healthy young adults (9 men, 8 women, mean ages 20 and 21 years). We used a Somatom Balance Scanner (Siemens, Erlangen) and the Siemens Osteo software. Scan parameters: Slice thickness 1 cm, 80 kV, 81 or 114 mAs. We measured the trabecular bone density and the area and height of the vertebra and calculated the volume and content of calcium hydroxyapatite (Ca-HA) in the trabecular substance of the first lumbar vertebra. RESULTS: Prepubertal boys had a mean bone density of 148.5 (median [med] 150.1, standard deviation [SD] 15.4) mg/Ca-HA per ml bone, and prepubertal girls had a mean density of 149.5 (med 150.8, SD 23.5) mg/ml. We did not observe a difference between prepubertal boys and girls. After puberty there was a significant difference (p < 0.001) between males and females: Mean density (male) 158.0, med 162.5, SD 24.0 mg/ml, mean density (female) 191.2, med 191.3, SD 17.7 mg/ml. The Ca-HA content in the trabecular bone of the first lumbar vertebra was 1.1 (med 1.1, SD 0.5) g for prepubertal boys and 1.1 (0.9, 0.4) g for prepubertal girls. For post-pubertal males, the mean Ca-HA content was 3.5 g, med 3.5, SD 0.5 g, and for post-pubertal females, the mean content was 2.8, med 2.7, SD 0.4 g. CONCLUSION: The normal trabecular bone mineral density is 150 mg/ml with a standard deviation of 20 mg/ml independent of age or gender until the beginning of puberty. Peak bone mass (bone mineral content) in the trabecular substance of the lumbar vertebral column is higher in males than in females, and peak bone density is higher in young female adults than in young male adults.

Absorptiometry, Photon↗

PubMed2001

Anatomic and physiologic reference values in least shrews (Cryptotis parva).

BACKGROUND AND PURPOSE: The least shrew is an established animal model for reproductive and pharmacologic research. Biologic reference data are needed to assess animal health status and provide a rationale for use of novel statistical programs to evaluate the effects of orally administered substances in toxicologic and pharmacologic studies. METHODS: Organ weights, blood biochemical and hematologic values, and food and water consumption data were collected from 50-day-old shrews after two weeks' consumption of a standard feline diet. RESULTS: In general, data correlated well with values reported for other mammalian species. Plasma phosphorus concentration was high. There was a significant difference in food and water consumption per gram of body weight between shrews at lower and upper (+/- 1 SD) weight ranges for the study. The 3.2-g animals consumed 27% more food per gram of body weight than did the 5.0-g animals. CONCLUSIONS: The high phosphorus concentration was attributed to hemolysis resulting from the axillary cut method of blood sample collection. The small size of the shrew allowed demonstration of the Kleiber effect within a +/- 1 SD weight range in a single species. The phenomenon necessitates the use of statistical methods other than the typical tests establishing the significance of the differences between the means of groups for oral toxicologic and pharmacologic studies.

Animals↗

PubMed1998

[Measurement of colonic transit time (total and segmental) with radiopaque markers. National reference values obtained in 192 healthy subjects. Spanish Group for the Study of Digestive Motility].

The interest for the technique of colonic transit time (CTT) measurement with radiopaque markers has been limited in our ambience, despite its documented clinical usefulness in evaluating patients with severe chronic idiopathic constipation. The aim of the present study was to contribute to the development of the technique by establishing the upper limit of CTT in a large series of healthy subjects in order to be used as national reference. Total and segmental CTT have been determined in 192 healthy subjects (114 men, 78 women; median age: 33 yr; range: 18-88 yr) recruited in 18 hospitals of Spain. CTT measurement has been carried out by means of daily administration of 20 radiopaque markers during three consecutive days and plain abdominal X-ray taken at 4th, 7th and, eventually, 10th day. The upper limit (95th percentile) of total, right, left and rectosigmoid CTT was, respectively, 71.2, 22, 37.2 and 37.2 h. Women had significantly longer transits than men for whole (p = 0.002), right and rectosigmoid (p = 0.01, respectively) colon and near to statistical significance (p = 0.076) for left colon. In this series, CTT were not related to age and geographic area. Correlation between results obtained in the first reading of X-ray done in each center and a second reading done by an independent observer, was excellent (p < 0.001). CTT measurement with radiopaque markers is a simple technique, attainable to different assistance settings. The obtained values are proposed as national reference given their independence from geographic area. When employing the technique to clinical evaluation of patients with constipation, the differences of CTT in function of gender should be kept in mind.

Adolescent↗

PubMed2002

Impact of age on reference values for serum concentration of cystatin C in children.

Recently, cystatin C (cyst C) was proposed for the assessment of glomerular filtration rate, being more accurate than creatinine determination. Reference intervals for cyst C do not vary with age and sex, like creatinine values. Elevated values of cyst C were reported for pre- and full-term infants. Nevertheless, the age cut-off for stable cyst C values i.e., age independence, remains under discussion. Therefore, we conducted a prospective study in 98 healthy children, 51 being under 18 months of age. Cyst C was determined by the nephelometric method. The infants under the age of 18 months had a higher mean serum cyst C value (0.94 +/- 0.24 mg/l) than the older children (0.65 +/- 0.19 mg/l). There was a negative correlation between age and cyst C in the infant group under the age of 18 months (r(2)=0.631, P<0.01). Our results indicate that mean serum cyst C is higher in infants than older children; the age cut-off appears over the age of 1 year of life, presumably reflecting kidney maturation. Our study does not allow accurate assessment of the age cut-off at 18 months or 36 months.

Aging↗

PubMedDate not supplied

[Comparison of the luminescence enhanced enzyme immunoassay Amerlite FT4/MAB-FT4 and Amerlite FT3/MAB-FT3 in blood serum of children. Reference values].

Concentrations of free thyroxine (n = 225, male = 124, female = 101) and free triiodothyronine (n = 60, male = 35, female = 25) were determined using the luminescence enhanced enzyme immunoassay methods Amerlite FT4/MAB-FT4 and Amerlite FT3/MAB-FT3 in blood-serum of children. In contrast to the excellent agreement of the results between the Amerlite FT4 and MAB-FT4 method, a significant difference was found between the Amerlite FT3 and MAB-FT3 results. Therefore it was necessary to establish new reference ranges for the MAB-FT3 method in childhood (cord blood = 50, n = 272, male = 183, female = 89).

Adolescent↗

PubMed2002

A contribution to the establishment of reference values for total mercury levels in hair and fish in amazonia.

Studies on mercury levels in the Amazonian Region have typically lacked background or reference parameters. A sectional study on Hg concentration in hair and fish was conducted, together with an assessment of the prevalence of signs and symptoms related to Hg poisoning, in four communities in the Amazon Basin not impacted by gold mining, located either by a river course (Santana do Ituqui and Caxiuanã) or by a lake (Aldeia do Lago Grande and Vila do Tabatinga). Mercury determinations in hair and fish were made by flameless atomic absorption spectrophotometry. Mean total Hg in hair was 4.33 microg/g (0.40-11.60 microg/g) in 321 individuals from Santana do Ituqui, 3.98 microg/g (0.40-11.76 microg/g) for 316 persons in Aldeia do Lago Grande, 5.46 microg/g (0.37-49.85 microg/g) for 504 individuals from Vila do Tabatinga and 8.58 microg/g (0.61-45.59 microg/g) for 203 inhabitants from Caxiuanã. Fish consumption was very high in all those communities but no signs or symptoms associated with Hg poisoning were found. Mean Hg concentration in fish varied from 0.006 to 2.529 microg/g for carnivores and from 0.008 to 0.871 microg/g for noncarnivores. These values suggest that further studies including a larger number of communities would eventually lead to values of "normal" Hg concentration in the Amazonian Region quite above the limits suggested by the World Health Organization.

Adolescent↗

PubMed2006

Reference values for cobalt, copper, manganese, and nickel in urine among women of the general population in Japan.

OBJECTIVE: The present study was initiated to establish the reference levels of Co, Cu, Mn, and Ni in urine of women in the general Japanese population. METHODS: Stored urine samples were subjected to the analysis. The samples were collected from 1,000 adult women all over Japan, who had no occupational exposure to these elements. Co, Cu, Mn, and Ni in urine were analyzed by graphite furnace atomic absorption spectrometry. The concentrations were distributed log-normally, and were presented in terms of geometric mean (GM) and geometric standard deviation, as observed or after correction for creatinine concentration or a specific gravity of urine of 1.016. RESULTS: The GM values of observed levels (i.e., with no correction for urine density) and of the levels after correction for creatinine (cr) concentration (values in parenthesis) were 0.68 g/l (0.60 microg/g cr) for Co, 13.4 g/l (11.8 g/g cr) for Cu, 0.14 microg/l (0.12 g/g cr) for Mn and 2.1 g/l (1.8 g/g cr) for Ni. There was a life-long age-dependent increase in Cu. Mn levels reached the maximum at 60 to 69 years of ages. In contrast, age-dependency was not substantial in Co and Ni. CONCLUSIONS: Comparison with values reported in literatures for other areas showed that Co and Ni levels in urine of Japanese women are higher than, Cu level is comparable with, and Mn level is lower than others. The reasons for high Co and Ni levels deserve further study.

Adult↗

PubMed1983

Assaying plasma prekallikrein (PPK) by a chromogenic based method: analytical considerations and reference values in healthy adults, the pregnant woman, and the neonate.

Analytical assays that measure the amidolytic activity of plasma kallikrein (PK) must overcome the problem of anti-kallikrein inhibition during the activation of PPK to PK. We resolved this problem by exposure of plasma to 50 mg/L dextran sulfate in acetone/water (35/65, vol/vol) at 0 degrees C for 15 minutes. PK activity was assayed using the chromogenic substrate, S-2302 (KABI). A centrifugal analyzer (CentrifiChem) was used to monitor the change in absorbance at 405 nm and 37 degrees C. The assay was linear to a value 3 times that found in normal human plasma. The specificity of the substrate for PK was demonstrated by using plasma deficient in PPK (Fletcher trait) diluted with normal human pooled plasma (NHPP). Day-to-day analytical variation was 2.4% for NHPP having a mean value of 85.9 mukat/L (n = 26). Using our amidolytic method, we determined PPK values in 50 healthy adults, 80 pregnant women during each trimester of gestation, and 151 neonates (cord blood specimens). The middle 95% reference interval for the adults was 54.0 - 118.8 mukat/L, for pregnant women at first trimester: 59.0 - 129.0, second trimester: 72.3 - 161.5, third trimester: 75.6 - 152.4, day of labor: 67.7 - 144.9, and 1-9 weeks postpartum: 69.4 - 151.0 mukat/L, and for the neonate: 11.5 - 44.9 mukat/L. We observed that women on oral contraceptives had significantly greater PPK values than those not on oral contraceptives. Intra-individual variation of PPK values was relatively low in non-pregnant women with the day-to-day coefficient of variation being 4.1 - 6.1% in 5 subjects monitored over a 30 day period. The high value of inter-individual/intra-individual ratio was appreciated in pregnant women in that the PPK value observed during the first trimester was a means to predict the value approaching term. The mean PPK value during the first trimester was 105.1% of the mean seen in non-pregnant women while the mean PPK value nearing term was 130.1% of that value.

Adult↗

PubMed2001

Toward a consensus on reference values for thyroid volume in iodine-replete schoolchildren: results of a workshop on inter-observer and inter-equipment variation in sonographic measurement of thyroid volume.

OBJECTIVE: Interpretation of thyroid ultrasonography for assessing goiter prevalence requires valid reference criteria from iodine-sufficient populations. Reports have suggested the current reference criteria for thyroid volume (T(vol)) of WHO/ICCIDD (International Council for the Control of Iodine Deficiency Disorders) may be too high. Our objective was to determine if inter-observer and/or inter-equipment variability contributes to the disagreement in sonographic T(vol) in children reported from iodine-sufficient areas. DESIGN: A 2-day workshop in which four experienced ultrasound examiners from around Europe measured T(vol) in 45 6--12-year-old Swiss schoolchildren using four different portable ultrasound machines. One of the participating examiners (observer A) had generated the T(vol) data in European children that are the basis for the WHO/ICCIDD reference criteria. METHODS: Sonographic T(vol) was measured in each child by all four examiners on all four machines. Six hundred and eighty-four examinations were completed, with examiners having no knowledge of one another's results. Inter-observer and inter-equipment variation was calculated. RESULTS: Mean inter-equipment variation in T(vol) was 15.2% (95% CI: 14.1, 16.3%). There were no significant differences in T(vol) between equipment (P=0.51). For all observers, the mean inter-observer variation in T(vol) was 25.6% (95% CI: 23.9, 27.2%). At all ages and all body surface areas, there was a large systematic measurement bias (+30% volume) between the mean T(vol) of observer A and the mean Tvol of observers B, C and D. Reanalysis using data from observers B, C and D reduced the mean inter-observer variation in T(vol) to 13.3% (95% CI: 11.9, 14.7%). A correction factor for the systematic difference of operator A for the P50 and P97 of T(vol) was estimated using analysis of covariance. When applied to the WHO/ICCIDD reference data, it sharply reduced the discrepancy between the WHO/ICCIDD criteria and those from other iodine-sufficient children around the world. CONCLUSIONS: Inter-equipment error contributes minimally to reported differences in sonographic T(vol). Even among experienced examiners, inter-observer variation in sonographic T(vol) in children can be high, and probably contributes to the current disagreement on normative values in iodine-sufficient children. A systematic bias at least partially explains why the WHO/ICCIDD reference data differ from those reported from other iodine-sufficient children around the world. The findings argue strongly for the standardization of methods used for sonographic measurement of T(vol) in children.

Child↗

PubMed2004

Reference values of pulmonary function tests for Canadian Caucasians.

A multicentre, cross-sectional study was carried out in six centres across Canada to establish a national standard for pulmonary function tests using healthy, lifetime nonsmokers, with each centre aiming to test 10 men and 10 women from each decade from 20 to 80 years of age. Data from each centre were used to derive prediction equations for each centre, and pooled data from all centres (total: 327 women and 300 men) were used to derive Canadian predicted equations. The predictive models were compared with three widely used published models for selected tests. It was found that, in general, the equations modelled for each centre could be replaced by the models obtained when pooling all data (Canadian model). Comparisons with the published references showed good agreement and similar slopes for most tests. The results suggest that pulmonary function test results obtained from different centres in Canada were comparable and that standards currently used remain valid for Canadian Caucasians.

Adult↗