Biomedical subjects

J Kestner

Publications and source records attributed to J Kestner.

15 recordsLinked to original sources

PubMed1992

Evaluation of two over-the-counter natural thyroid hormone preparations in human volunteers.

OBJECTIVE: To determine the pharmacologic activity of over-the-counter (OTC) thyroid preparations. DESIGN: In vitro analysis and a prospective, crossover study in vivo. SETTING: Tertiary care center. PARTICIPANTS: Two healthy adult volunteers. INTERVENTION: Three OTC preparations (Thyrotrophin PMG [bovine thyroid PMG extract], Thyro Forte [thyroid lymphogland concentrate with synergistic complex], and Thyro Complex [thyroid lyophilized gland concentrate with synergistic complex]) were analyzed in vitro. Volunteers were administered two times the manufacturer's maximum recommended daily dose of either Thyrotrophin PMG or Thyro Forte for one week, washed out for four to five weeks, and crossed over to receive the opposite tablet preparation for an additional week. MAIN OUTCOME MEASURES: The triiodothyronine (T3) and thyroxine (T4) contents of OTC preparations were measured by HPLC. Vital signs, serum total and free T4, total T3, thyroid stimulating hormone, thyroxine binding globulin, thyroglobulin, and general chemistry tests (including glucose and cholesterol) were monitored before, during, and between administration of the products. RESULTS: HPLC analysis of the three OTC preparations showed no T4 but did show possible T3 in two of these products. We found no definite clinical or laboratory evidence of thyroid hormone excess with either product. CONCLUSIONS: Healthcare professionals should advise against the use of these scientifically unsound and relatively expensive OTC thyroid preparations, of which the therapeutic efficacy is unknown.

Drug Evaluation↗

PubMed1990

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. III. Analysis of interference variables by stepwise regression.

We applied stepwise regression for multivariate analysis of data for free thyroxin (FT4) in serum and for other laboratory tests of thyroid function in patients with nonthyroidal illness. Using the maximum R2 improvement and backward elimination methods to test five variables [prealbumin, albumin, T4-binding globulin (TBG), free fatty acids (FFA), and FFA/albumin molar ratio], we found that the variables with the greatest predictive power clustered according to the methodology of FT4 measurement. Thus, we best predicted the FT4 results obtained by 16 techniques as follows: FT4 measured by one-step (analog) RIAs, with albumin; FT4 determined by two-step (sequential) RIAs, with FFA or FFA/albumin molar ratio; FT4 estimated by a binding-rate-based RIA or conceptually related FT4 indices [based on triiodothyronine (T3) uptake], with TBG; FT4 measured by equilibrium dialysis, with TBG and FFA/albumin molar ratio; and T4/TBG ratios, with either none or prealbumin and albumin. We could very highly (P less than 0.001) predict total T4 and T3 by considering TBG, and total T3 also by considering prealbumin and albumin, whereas reverse T3 was predictable with prealbumin only (negative relationship). We found comparatively weak associations between thyrotropin (TSH) and albumin or TBG. In clinical practice, abnormalities in key variables should call attention to possible effects of these variables on FT4 and other thyroid-test results and thus to the need for appropriate correction or alternative testing.

Carrier Proteins↗

PubMed1989

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. I. Effect of free fatty acids.

We examined the effect of endogenous free fatty acids (FFA) on the measurement of free thyroxin (FT4) by five different methodologies represented in 16 different assays in a large number of patients with nonthyroidal illness (NTI). Some, but not all, one-step (analog) FT4 RIAs negatively correlated with FFA concentration. All two-step FT4 RIAs, equilibrium dialysis FT4, and the dialyzable (free) fraction of T4 positively correlated. In contrast, a binding-rate-based FT4 RIA, FT4 indices based on T3 macroaggregated albumin uptake, and T4/TBG ratios did not correlate. We also analyzed the FT4-FFA relationship with a second, more sensitive approach by correlating test results with FFA/albumin molar ratio as an estimate of the "excess" (nonalbumin bound) FFA. We found that all FT4 RIAs, equilibrium dialysis FT4, FT4 indices based on T3 uptake, the dialyzable fraction of labeled T4 in equilibrium dialysis, the fraction of labeled T4 bound to solid phase antibody in the binding-rate-based RIA, and T3 uptake correlated with the FFA/albumin molar ratio. This FFA dependency was comparable among all the various techniques and was relatively small. Thus, increases or decreases in FT4 results due to varying FFA (and albumin) concentrations are highly likely with most currently available methods (only the T4/TBG ratio did not reveal FFA-dependency), but the magnitude of changes varies with the "excess" FFA.

Dialysis↗

PubMed1989

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. II. Effect of prealbumin, albumin, and thyroxin-binding globulin.

We studied the correlation of thyroxin (T4)-binding proteins with the apparent free T4 (FT4) in 101 patients with nonthyroidal illness (NTI). Most patients (95%) were seriously ill at the time of blood collection. Concentrations of T4-binding prealbumin (transthyretin), albumin, and T4-binding globulin (TBG) often were low in the sera of these patients. Albumin was the most frequently subnormal, TBG the least. FT4 in serum was determined by five methods represented in 16 different assays. With few exceptions, analog (one-step) FT4 RIAs--both the binding-rate-based RIA and the related FT4 indices (calculated from triiodothyronine-macroaggregated albumin uptake and total T4)--and T4/TBG ratios correlated positively and usually highly significantly (P less than 0.01) with concentrations of prealbumin, albumin, and TBG. Equilibrium dialysis values for FT4 did not correlate with prealbumin concentrations but showed a weakly (P less than 0.03) positive association with albumin and a highly significant (P less than 0.002) positive correlation with TBG. Of the three two-step FT4 RIAs tested, the only statistically significant but weakly (P less than 0.02) positive correlation with T4-binding proteins was between Spiria FT4 and TBG. Thus, in these NTI patients, FT4 estimates vary with methodology and, to a lesser extent, with the particular assay used. The results from two-step FT4 RIAs are least associated with binding protein concentrations.

Humans↗

PubMed1986

Comparison of automated and manual methods for urinalysis.

The authors compared results for accuracy and precision obtained by a semiautomated prototype International Remote Imaging Systems, Inc. (IRIS) urinalysis workstation (IUW) with those from quantitative manual urinalysis (QMU). Three technologists skilled in urinalysis each performed 172 urinalyses with both the IUW and QMU methods. The results show that the IUW method is likely to yield comparable counts for particulate analytes compared with the QMU, except for casts. The QMU reported significantly (P less than 0.001) more casts than the IUW method. This difference is related to at least a ninefold greater volume of untreated urine examined by the QMU method than the IUW method. The IUW method may provide a more accurate result than the QMU method at very low and high concentrations of particulate analytes. The result from 24 blind duplicate urines also analyzed by each of the three technologists with both methods showed comparable precision for particulate analytes between the two methods except for red blood cells; the QMU method had significantly (P less than 0.001) better precision for this analyte.

Automation↗

PubMed1986

Automated determination of urinary creatinine without sample dilution: theory and practice.

The rate of the Jaffé reaction depends on the concentration of sodium hydroxide; the pseudo-first-order rate constant of the reaction, at 37 degrees C in 10 mmol/L picrate solution, is 0.004 mmol/L. We formulated an automated method to determine urinary creatinine directly without manual sample dilution. The conditions are as follows: 10 mmol/L picrate and 60 mmol/L sodium hydroxide (final concentrations); ratio of sample to final volume, 1:41; temperature, 37 degrees C; wavelengths of measurement, 500 or 510 nm; interval of measurement, 30 to 90 s; and mode of measurement, kinetic. Determinations of creatinine in patients' samples by the new method compared favorably with those obtained with the AutoAnalyzer and aca. The run-to-run CVs were 3.6% or less, and the method was accurate for concentrations of creatinine up to 3000 mg/L. We recommend this method as a good replacement for the AutoAnalyzer or aca methods.

Autoanalysis↗

PubMed1985

Four methods for determining total protein compared by using purified protein fractions from human serum.

The proportional bias of four methods frequently used for determining low concentrations of protein was evaluated with human serum protein fractions (Cohn Fractions II, III, IV, and V). Each fraction was assigned a protein concentration value as determined by the biuret method, calibrated with purified human serum albumin monomer. All four methods (Coomassie Brilliant Blue dye-binding, the method of Lowry et al., ultraviolet absorption, and immunonephelometry gave acceptable results for Fraction V (albumin). The ultraviolet absorption and the Lowry methods overestimated the three globulin fractions (II, III, and IV), whereas the other two methods underestimated these fractions. The method of Lowry et al. gave the least proportional bias for the globulin fractions.

Blood Proteins↗

PubMed1978