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At least 973 records · Page 54Linked to original sources
PubMed1993

Plasma carnitines: reference values in an ambulatory population.

Carnitine was determined radioenzymatically in the plasma of 415 hospital employees involved in a screening programme for prevention of major cardiovascular risks. A reference population (N = 340) was extracted after excluding subjects with hypertension, diabetes mellitus or treatment for hypercholesterolaemia. This population showed a Gaussian distribution for total and free carnitine concentrations both in females and males but not for acyl carnitine or the acyl/free ratio. Females had lower total and free carnitine concentrations but a higher ratio of acyl/free carnitine than males. These differences were not detectable in older subjects (35 years for the acyl/free ratio, 45 years for total and free carnitine concentrations). Females with a body mass index > 28 had a lower acyl/free ratio than their respective controls. The differences in carnitine concentrations indicate that sex and age should be matched in patients or experimental groups and controls in studies involving carnitine plasma concentrations.

Adult↗
PubMed1989

[Are hematologic reference values applicable to the healthy elderly?].

In the healthy elderly (65-90 years; 80 men, 75 women) the variability of haematological findings was examined and compared with the reference range. In the men, the ranges for haemoglobin valves (7.4-10.5 mmol/l) and erythrocyte counts (3.8-5.5 x 10(12)/l) proved to be lower than the reference intervals (8.5-10.9 mmol/l and 4.4-6.0 x 10(12)/l respectively). For the women no discrepancies were found. The question arises whether the reference limits for haemoglobin and erythrocytes should be lowered for elderly men.

Aged↗
PubMed1994

The impact of gender and puberty on reference values for urinary growth hormone excretion: a study of 3 morning urine samples in 517 healthy children and adults.

Some recent studies have indicated that measurement of urinary GH (U-GH) excretion may be a useful tool for the evaluation of GH insufficiency in children with growth disorders, although some investigators are skeptical about the diagnostic value of U-GH. Most current assays are only available for specific laboratories or require time-intensive pretreatments of the specimens. This limits the possibility for many centers to compare their patients' data with others or to establish their own reference ranges for U-GH excretion. Therefore, we investigated the performance of a commercially available kit, which allows direct measurement of U-GH in untreated urine specimens. We established a reference range for the geometric mean of 3 morning urine samples in 446 healthy children and 71 adults. U-GH could be determined in all but 9 of 1526 samples (99.4%). U-GH excretion was significantly dependent on pubertal maturation (P < 0.001) and sex (P < 0.001), whereas age had no significant influence in the prepubertal group (P > 0.3). Peak values occurred in Tanner stages 3 and 4 (369 and 391 pg/h in females; 503 and 882 pg/h in males), corresponding to an age interval of 11-18 yr in boys and 9-15 yr in girls. Short collection periods (< 6 h) were related to low values for U-GH excretion (nanograms per night; P < 0.02). This time effect disappeared if U-GH excretion was expressed as picograms per h. If U-GH was related to creatinine output, there was a decrease in U-GH excretion during prepuberty, a blunting of the pubertal peak, and lower values in adults than in prepubertal children (P < 0.0002). The intraindividual variation in U-GH excretion (picograms per h) ranged from 40-61%, constituting approximately two thirds of the interindividual variation. This variation was not lowered by relating U-GH to creatinine. We conclude that the assay was suitable for measurement of U-GH excretion in virtually all healthy volunteers. Sex and pubertal stage as well as urinary volume and clock times for collection periods should be registered when establishing a reference range for U-GH excretion and applying it for clinical purposes. Our reference values may be useful for further studies of patients with GH disorders.

Adolescent↗
PubMed1995

Midtrimester human chorionic gonadotropin levels: normal reference values in Chinese pregnant women.

In order to establish normative median values of maternal serum total human chorionic gonadotropin (hCG) at our own laboratory, 2711 normal sera were collected from uncomplicated, singleton Chinese pregnant women, including 1705 samples measured by radioimmunoassay (RIA) between 13 and 24 weeks' gestation and 1006 samples measured by enzyme immunoassay (EIA) between 14 and 20 weeks' gestation. The hCG secretion pattern throughout midtrimester measured by RIA is similar to that of measured by both RIA and EIA have a steep drop initially and then steadily decline from 17 weeks of gestation. The total (hCG levels measured by RIA and EIA showed different normative median values and distribution. If it was measured by RIA between 14 and 20 week's gestation, there were 3.7% and 17.8% of pregnancies with serum total hCG levels less than 0.25 multiple of the median (MoM) and 0.5 MoM, retrospectively, and 11.6% and 5.5% among them with serum levels above 2.0 MoM and 2.5 MoM, respectively. When it was measured by EIA, there were 0.7% and 9.2% of pregnancies with serum total hCG levels less than 0.25 MoM and 0.5 MoM, respectively, and 8.9% and 3.7% among them with serum levels above 2.0 MoM and 2.5 MoM, respectively. Accurate and satisfactory interpretation of maternal serum screening for Down syndrome depends on establishment of a well-developed normative median value for each week of gestation. Any laboratory intends to provide hCG for maternal serum screening should have its own reference data by its own immunoassay method.

Chorionic Gonadotropin↗
PubMed2001

Reference values of fetal aortic flow velocity waveforms and associated intra-observer reliability in normal pregnancies.

OBJECTIVES: It was the aim of the present study to calculate new Doppler reference ranges for blood flow velocities (Vmax, Vmean, Vmin) and resistance indices (PI, RI) for the fetal descending aorta by automatic waveform analysis. DESIGN: Cross-sectional prospective study. SUBJECTS: Nine hundred and twenty-six low-risk pregnancies at 18-41 weeks' gestation. METHODS: Aortic blood flow velocities were derived with pulsed-wave color Doppler. Measurements were carried out at the level of the diaphragm. Reference ranges for the individual measuring parameters were constructed based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square principle. Further investigated were intra-observer reliability and the influence exerted by different measuring sites (aortic arch, diaphragm, below the renal vessels) on the aortic Doppler flow spectrum. RESULTS: Although a significant increase in aortic blood flow velocity was observed at 18-41 weeks' gestation (Vmax = 48.2 cm/s to 110.3 cm/s (P < 0.001), Vmean = 20 cm/s to 47.5 cm/s (P < 0.001) and Vmin = 7.6 cm/s to 18.6 cm/s (P < 0.001)), there were no significant changes in the pulsatility or resistance indices. The resistance indices PI and RI as well as absolute blood flow velocities (Vmax, Vmin) were significantly lower with increasing distance from the heart. Initial decreases were measured between the aortic arch and the diaphragm: PI, 2.34 to 1.87 (P < 0.0001); RI, 0.87 to 0.79 (P < 0.0001); Vmin: 8.5 cm/s to 15.0 cm/s (P < 0.0001). Furthermore, systolic blood flow velocities (Vmax) were decreased below the renal vessels from 97 cm/s to 64 cm/s (P < 0.0007). No significant changes were recorded in intensity-weighted mean flow velocities (Vmean). The intra-observer reliability was low, but of no clinical relevance. CONCLUSIONS: At constant measuring conditions, the reference ranges for blood flow velocities and resistance indices in the fetal aorta calculated by the authors serve as the basis for Doppler ultrasound antenatal examinations in a normal patient population and enable the early diagnosis of fetal risk.

Aorta, Thoracic↗