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Biomedical subjects

K O Pedersen

Publications and source records attributed to K O Pedersen.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1983

Blood ionized calcium measurements during aortocoronary bypass graft operations.

Electrode technology has made it feasible to measure and report arterial blood ionized calcium (Ca++) simultaneously with arterial blood gases and pH during aortocoronary bypass graft operations requiring prolonged (duration 1.23-4.43 hours) extracorporeal circulation and moderate hypothermia (25-28 degrees C). Blood Ca++ in 22 consecutive patients remained surprisingly constant at a moderately hypocalcaemic level despite the multiplicity of disturbing factors, but rewarming and blood transfusion did cause a small, but significant decline of blood Ca++. Management of patients has been changed by routine availability of close to real time Ca++ measurements, which are more convenient and faster in this situation than plasma total calcium, which is meaningless or even misleading.

Calcium↗
PubMed1979

Unconjugated thyroxine and triiodothyronine in urine: influence of age, sex, drugs and thyroid function.

The 24 h urinary excretion (dU) of T4 and T3, determined by radioimmunoassays using extraction and separation on Sephadex columns, is higher in men than in women (mean dU-T4 and dU-T3 +/- 2 SD: 2.6 +/- 0.9 vs. 2.2 +/- 1.0 and 2.5 +/- 1.0 vs. 2.0 +/- 0.8 nmol, respectively). The excretion of T3 decreases with age, but expressed relatively to dU-creatinine there is no effect of age and sex. Children have increased T4 and T3 to creatinine excretion ratios and neonates excrete predominantly T4. Oestrogens, acute salicylate loading and diurnal variation yielded results, which were at variance with the hypothesis that dU-T4 and dU-T3 mirror corresponding free hormone concentrations in serum, and there was only a weal positive correlation to total serum hormones in thyrotoxicosis as well. General clinical use of urine T4 and T3 is obviated by poor diagnostic discrimination and inherent analytical and interpretative disadvantages.

Adolescent↗
PubMed1978

An analysis of measured and calculated calcium quantities in serum.

Potentiometrically measured ionized calcium (Ca2+) was compared with total and albumin corrected S-Calcium and calculated Ca2+ in serum samples from blood donors and patients, for whom a request of S-Calcium has been made. Total S-Calcium, Ca2+ and S-Albumin in donors conformed with a simple mass law equation with a mean KCaAlb = 95 l/mol, whereas apparent albumin binding affinity rose with decreasing S-Albumin in patients (due to rise of other calcium binding proteins) with resulting overestimation of albumin corrected and particularly of calculated Ca2+. The frequency and severity of hypoalbuminaemia in patients make calculated Ca2+ unreliable and albumin corrected S-Calcium the clinically most satisfactory routinely practicable substitute for direct Ca2+ measurement.

Adolescent↗