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J Thode

Publications and source records attributed to J Thode.

At least 37 records · Page 2Linked to original sources
PubMed1989

Comparison of serum total calcium, albumin-corrected total calcium, and ionized calcium in 1213 patients with suspected calcium disorders.

The correlations between serum ionized calcium, serum total calcium, total calcium corrected for albumin and calculated ionized calcium were investigated in a prospective multicentre investigation of 1213 patients suspected of having calcium metabolic disease. Diagnostic discordance between serum total calcium and measured ionized calcium was found in 31% of the patients. With the calculation of albumin-corrected total calcium or calculated ionized calcium the discordance decreased to 17.9%. The diagnostic discordance which could be ascribed to the analytical imprecision (CV = 1.5%) amounted to only 6.7%. Although we found highly significant correlations between the parameters, a considerable scatter around the regression line made prediction of ionized calcium from albumin-corrected total calcium unreliable in many patients.

Algorithms↗
PubMed1988

Simplified protocol for biochemical evaluation of recurrent renal calcium stone disease.

Groups comprising 42 recurrent and 38 single calcium stone formers, and 48 controls underwent a standardized study protocol. During 12 h of fasting along with a standardized water load urine was collected for the last 4 h. One blood sample was drawn midway during urine collection. As compared with controls recurrent stone formers demonstrated significantly raised values of plasma ionized calcium, 1,25-dihydroxyvitamin D [1,25-(OH)2D], urinary ionized calcium, urinary pH, and standardized excretion rate of calcium [ECa(U)]. The tubular reabsorption of sodium and chloride, the maximal tubular reabsorption of phosphate, nephrogenous cyclic AMP (NcAMP), glomerular filtration rate (GFR) and plasma albumin were all significantly depressed. Data from the single stone former group were intermediate between controls and recurrent stone formers. For the pathogenesis of recurrent calcium stone formation these data suggest a general, though variably expressed, defect in the proximal tubular reabsorption of calcium, phosphate, bicarbonate, sodium and chloride leading to hypersecretion of 1,25-(OH)2D, hyperabsorption of calcium from the gut and a modest increase in plasma ionized calcium. Computer analysis of data do not support the concept that stone patients can be classified as either intestinal hyperabsorbers or renal losers. A stepwise discriminant analysis selected plasma albumin, urinary pH, ECa(U), plasma phosphate, GFR and NcAMP as the most important variables contributing to the difference between controls and recurrent stone formers. By this procedure we obtain a sensitivity of 93% and a specificity of 96% respecting proper classification of the recurrent stone former. The analysis may therefore be of value predicting the risk of recurrent stone formation in the single stone former.

Adolescent↗
PubMed1988

Six direct radioimmunoassays of estradiol evaluated.

We evaluated the analytical performance of six commercial direct radioimmunoassays of 17 beta-estradiol, those from Radioassay Systems Laboratories, IRE Medgenix, Biotecx Laboratories, Farmos Spectria, International CIS, and Diagnostic Products Corp. The mean value for estradiol (E2) and the within- and between-run CVs were determined for serum pools and control materials, measured in seven to 10 runs with each method. Mean values for E2 in pooled sera deviated by 75% to 350% from the means measured with our routinely used extraction method. Between-run CVs ranged from 4% to 14% for the direct assays as compared with 10% for the extraction assay. We also investigated, for two of the direct assays, the effect of extraction with diethyl ether before radioimmunoassay, with respect to improvement in the agreement with our extraction method. All of the assays were easy to perform and results were obtained within 4-5 h, but we conclude that matrix effects may be expected in direct assays of estradiol.

Estradiol↗
PubMed1987

Effect of tetrasodium EDTA on enzymatic determinations of urinary oxalate.

We studied the effects of pretreating urine samples with tetrasodium EDTA (TEDTA) before measuring urinary oxalate with an enzymatic kit (Sigma). Mean analytical recovery of added oxalic acid was only 49% (SD +/- 13%) when the assay was performed as recommended by the manufacturer, but treating samples with TEDTA improved recoveries (96 +/- 10%). In 20 unselected 24-h urine samples assayed with and without TEDTA treatment, the mean oxalate concentrations were significantly (P less than 0.001) different: 15.6 +/- 8.7 and 12.2 +/- 7.9 mg/L, respectively. TEDTA-treated urine samples stored for 14 days at -20 degrees C lost 20% of their oxalate concentration. Use of TEDTA simplifies sample preparation by eliminating the alkalinizing step needed to dissolve EDTA or disodium EDTA.

Edetic Acid↗
PubMed1987

Activity measurements of calcium, sodium, potassium, and chloride after equilibrium dialysis used to show lack of evidence for protein interference with calcium electrodes.

We measured the activity of Ca2+, Na+, K+, and Cl- with ion-selective electrodes after equilibrium dialysis of solutions with different albumin concentrations. The calculated Donnan ratio was the same for all ions in the same solution and increased with the albumin concentration, as predicted by the Donnan theory. The Donnan distribution ratio for Ca2+ was similar, as determined with instruments from three different manufacturers. For healthy subjects and patients with renal stone disease, we did not find any correlation between serum concentrations of ionized calcium and albumin. The discordance between measured ionized calcium and albumin-corrected total calcium depended on the correction algorithm we utilized. The difficulties of absolutely proving or disproving a protein error in these measurements are discussed, but our data are not consistent with protein being a source of error in measurements of ionized calcium.

Adult↗
PubMed1986

Actual ionized calcium and pH in blood collected in capillary or evacuated tubes.

Results are presented for the concentration of actual ionized calcium (cCa2+), the actual pH and ionized calcium at pH = 7.4 [cCa2+(7.4)] measured in capillary whole blood, venous serum from vacuum tubes (Venoject) and serum equilibrated to pCO2 approximately equal to 5.3 kPa from 57 renal patients. The mean value for cCa2+ was higher for venous serum than for capillary blood (1.29 mmol/l versus 1.26 mmol/l), corresponding to the difference in pH (in venous serum). This difference could be eliminated by separating the serum at 4 degrees C rather than room temperature. The cCa2+ (7.4) was the same for capillary blood, venous serum (Venoject) and equilibrated serum from blood collected in plain glass tubes, Venous serum could be stored at 4 degrees C for 4 h without significant change in cCa2+ and pH, and for 1 week at 4 degrees C for the measurement of cCa2+(7.4). In patients with acid-base disturbance cCa2+ is preferable to the measurement of cCa2+(7.4).

Blood Specimen Collection↗
PubMed1985

Changes in vitamin D metabolites and bone histology in rats during recovery from rickets.

The relative roles of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-(OH)2D) and 24,25-dihydroxyvitamin D (24,25-(OH)2D) in bone mineralization are largely unknown. Young vitamin D depleted rats were fed increasing amounts of vitamin D and grouped radiologically in accordance with the rat line test. They ranged from severely rachitic to normal. Radiology was correlated with serum levels of 25-OHD, 1,25-(OH)2D, 24,25-(OH)2D, ionized calcium, magnesium, and phosphate, with bone histology, and with the total mineral content of the animals. Serum 1,25-(OH)2D rose in a linear fashion to supranormal values during bone healing and correlated with the radiological degree of rickets. Serum 25-OHD was below detection limit in the most rachitic and low in the radiologically normal rats, whereas 24,25-(OH)2D was low in all groups. These two metabolites showed no correlation with the radiologic, histologic or biochemical parameters. In rachitic rats, 1,25-(OH)2D appears to play a major role in bone healing and possibly exerts a direct effect on bone cells. It cannot be ruled out, however, that the effect is mediated through a rise in serum levels of calcium and phosphorus, although signs of bone healing were seen in the presence of a subnormal calcium X phosphorus product. Initiation of mineralization can take place with unmeasurable 25-OHD, and 24,25-(OH)2D seems to be without importance.

Animals↗
PubMed1985

Sampling and storage of blood for determination of ionized calcium.

We report some new procedures for the determination of ionized calcium using a semi-automatic ICA 1 analyser provided with a new flow-through tonometer unit, TNC 1, in connection with an automatic turntable. Ionized calcium calculated to a standard pH of 7.4 (cCa2+(7.4)) was not significantly different for capillary blood, venous blood and serum in healthy adults; however, a significant difference was found for actual ionized calcium (cCa2+). The effect of erythrocytes on the liquid junction potential was eliminated by use of a new salt bridge solution (sodium formate). Serum samples should be taken as anaerobically as possible to avoid precipitation of calcium complexes when pH increases above 7.9. For measurement of cCa2+-pH we developed special capillary tubes. Serum could be stored at 4 degrees C for 7 days and at -20 degrees C for 45 days without significant change in cCa2+(7.4). Capillary blood could be stored at 4 degrees C for 4 h without significant change in cCa2+ and pH or at 4 degrees C or 20 degrees C for 24 h without significant change in cCa2+(7.4). Vein puncture with stasis or muscular exercise caused only a small increase in cCa2+(7.4) (1.5%). The ingestion of food did not affect cCa2+ in healthy adults. 97.5% CO2 equilibrium was obtained in 3 min with the new flow-through tonometer.

Air↗
PubMed1985

Urinary cyclic AMP in spot urine of healthy children.

We present reference values for the excretion of cAMP in spot urine collected between 09.00 and 12.00 hours in 143 healthy children aged 2-200 months. The excretion of cAMP was creatinine-corrected and expressed as a substance concentration ratio (UcAMP/crea)U due to a positive significant correlation between the excretion of cAMP and creatinine (r = 0.68, p less than 0.001). The mean value (95% significance limits) for (UcAMP/crea)U was 748 mumol/mol (254-2206 mumol/mol). A logarithmic transformation of the ratio was used, since preliminary analysis showed uneven distribution; when the logarithmic transformation was used, the data appeared evenly distributed. There was no significant difference between the results for girls and boys. The value of lg(UcAMP/crea)U was related to the age or body surface area with decreasing values at higher age or body surface area. (r = -0.55 and r = -0.57, p less than 0.001). Spot urine for measurement of urinary cAMP instead of a 24 h collection appears preferable due to the practicability of the test in children.

Adolescent↗
PubMed1985

Measurement of ionized calcium with five types of instruments. An external quality assessment.

An external quality assessment for ionized calcium determinations was carried out in 24 laboratories in Northern Europe. Both protein-free and protein-containing test materials were included in the study. The average within-laboratory variation (CV) for all test materials was 3.1, 1.7, 1.2, 1.8 and 1.3% for the AVL 980 (AVL, Graz, Austria), the Microlyte (Kone, Espoo, Finland), the Nova 2 (Nova Biomedical, Newton, Ma USA), the Orion SS-20 (Orion, Cambridge, Mass., USA), and the ICA1 (Radiometer, Copenhagen, Denmark) respectively. The corresponding interlaboratory CV was 3.1, 2.9, 3.1 and 2.4%. The variation between types of instruments was even larger and caused differences of up to 33%. The results indicate a need for well-defined protein-containing control material.

Calcium↗
PubMed1985

The calcium ion activity and the standardized excretion rate of calcium in urine of healthy adults.

A standardized protocol is described for the study of the calcium excretion in urine. After 12 h of fasting, urine is collected during 4 h with a water load of 10 ml per kg body weight. Urine is also collected during the following 20 h period on the habitual water and calcium intake. Reference values for 48 healthy adults are given as 0.25 and 0.75 quantiles. The measured activity of calcium ions (Ca2+) in urine is 0.09-0.27 mmol/kg for the 4 h period, 0.34 to 0.52 mmol/kg for the 20 h period; pH values are 5.61-6.43 (4 h) and 5.46 to 6.04 (20 h). The concentrations of total calcium are 0.67-2.05 mmol/l (4 h) and 3.16 to 4.94 mmol/l (20 h). The value for the excretion rate of calcium (standardized to a creatinine clearance of 100 ml/min) is 1.30-3.24 mumol/min for the 4 h period and 3.06-4.88 mumol/min for the 20 h period, with no significant difference between the results for men and women. The relationship between the Ca2+ activity and pH was studied in urine titrated with HC1 or NaOH. In all urine the Ca2+ activity falls with increasing pH in a typical biphasic manner. This indicates the need for simultaneous measurement of the pH in order to interpret data for the Ca2+ activity in urine.

Adult↗
PubMed1984

Extraction from bone powder: collagen, calcium and phosphate.

A method for the estimation of the extraction rate is shown and exemplified by preliminary data from extraction of collagen, calcium and phosphate with EDTA and neutral salt solution. The initial extraction rate was high, even with neutral salt solution, and optimal extraction efficiency was obtained within 24 h.

Bone and Bones↗
PubMed1984

Serum ionized calcium, nephrogenous and total urinary cyclic AMP and urinary phosphate in normal subjects.

Total urinary cyclic AMP (UcAMP) and nephrogenous cyclic AMP (NcAMP) were measured in 4, 20 and 24 h urine in forty-eight healthy volunteers. There were no significant differences between 4, 20 and 24 h excretion rate of UcAMP and NcAMP whether it was corrected for the glomerular filtration rate [( UcAMP]GF, [NcAMP]GF), creatinine corrected (UcAMP/Crea)U, or expressed as actual excretion rate (NcAMP,n), nor any sex differences. Mean values +/- one standard deviation (SD) for these parameters: [UcAMP]GF: 30.4 +/- 9.4 nmol/l; 27.7 +/- 7.0 nmol/min; 28.1 +/- 6.9 nmol/l in 4, 20 and 24 h urine, respectively. [NcAMP]GF: 13.4 +/- 8.5 nmol/l; 10.6 +/- 7.7 nmol/l; and 11.1 +/- 7.2 nmol/l in 4, 20 and 24 h urine, respectively. (NcAMP,n): 1.45 +/- 0.90 nmol/min; 1.14 +/- 0.80 nmol/min; 1.17 +/- 0.73 nmol/min in 4, 20 and 24 h urine, respectively, NcAMP accounts for about 40% of UcAMP. A positive correlation was found between plasma cyclic AMP and [UcAMP]GF (r = 0.41, P less than 0.001), whereas this relationship could not be demonstrated between plasma cyclic AMP and [NcAMP]GF (r = -0.008, P greater than 0.1). The calculation of [NcAMP]GF therefore corrects for unsuspected high or low plasma cyclic AMP values, and is therefore the preferred parameter of the PTH effect on the kidney tubular cells. No correlation could be demonstrated between [NcAMP]GF and concentration of ionized calcium in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Sex-dependent relation between ionized calcium in serum and blood pressure.

In an epidemiological study of 977 45-year-olds, both the mean concentration of ionized calcium in serum, [Ca2+]7.4, and arterial blood pressure were higher in men than in women. Among the men, there was a weak positive correlation between [Ca2+]7.4 and the systolic blood pressure, but no other significant correlation was found within each separate sex. Postmenopausal women had slightly increased [Ca2+]7.4 but normal blood pressure. Patients taking thiazide diuretics or beta-adrenergic blocking agents had normal [Ca2+]7.4.

Blood Pressure↗
PubMed1984

Determination of sodium and potassium with ion-selective electrodes.

We compared different sample-handling techniques for measurement of Na+ and K+ with ion-selective electrodes (ISE). Imprecision was less for venous blood (with a minimum of heparin) than for plasma, serum, or capillary blood. The results for K+ were higher for serum than for whole blood, and higher for whole blood than for plasma. The latter difference was apparently due to release of K+ during the analysis. Values were more stable for whole blood stored at 20 degrees C than at 4 degrees C or 37 degrees C. The molality of Na+ in the plasma of mixed whole blood changed by -10.5 mmol/kg per unit change in blood pH. This could be explained by the different H+ buffering capacities of plasma and erythrocyte fluid, because when the pH is changed, the concentration of small anions in erythrocytes changes more than it does in plasma, with a consequent osmotic movement of water across the erythrocyte membrane. When we took into account the residual liquid-junction potential and the mass concentration of water in each of 65 patients' sera, the molality determined for Na+ was 1% lower and that of K+ 3% lower by ISE than by flame photometry--differences that may be related to ionic binding or to a lower molal activity coefficient in serum than in the calibrator.

Capillaries↗
PubMed1983

Relation between ionised calcium and pH in infants with acute acid-base disturbances.

Plasma ionised calcium, [Ca2+], and pH were negatively correlated in 21 infants with disturbed acid-base homeostasis. The slopes of the individual regression lines indicated a mean decrease in [Ca2+] of 42% per pH increase. (Mean delta log[Ca2+]/delta pH = -0.184, SEM = 0.050, p less than 0.001). The value was not significantly different from the relation between [Ca2+] and pH in vitro, when whole blood or plasma was equilibrated with CO2-air mixtures. pH and [Ca2+] must be measured and considered together to allow a proper interpretation of the result.

Acid-Base Imbalance↗