Stability of Thyroid Function Test Analytes Whose Serum Levels Are Determined by Immunoassay

We have performed stability studies on thyroid function tests, i.e., T4, T3, free T3 and stimulating hormone (TSH), over a five-day period the sera of ten patients. find that levels for each analyte were stable; mean coefficients variation (CV) ranged from 3.2 % TSH to 8.7% T4. ANOVA statistical analysis group means indicated there was no statistically significant difference in these means, confirming reproducibility values. On other hand, CVs are significantly larger than those found our prior critical analytes such as electrolytes (sodium, potassium, chloride, calcium). In addition, variations values occurred T4 which showed largest five studied. one patient, low <10 ug/dL 14 period. A two-tailed t test comparing CV with four lower indicating assay yield most precise results. These results parallel obtained electrolyte study very sodium, potassium chloride higher calcium. Since approximately half total serum calcium is bound albumin since high percentages (≥99%) binding globulin albumin, protein may introduce possible source imprecision.