Serum Analytes

A.  Hormones and markers of inflammation.  The Core routinely conducts the assays listed below. For each assay, the serum volume required (µl), lowest detectible concentration, and mean intra- and inter-assay coefficients of variation (CV) are provided. The indicated CVs are derived from in-house assays. Assays are for human hormones unless otherwise specified.

Adiponectin (human):  Double-antibody RIA (Linco Research, Inc., St. Charles, MO); 100 µl sera; 1.0 ng/ml; intra-assay CV: 5.4%; inter-assay CV:6.3%. Multimeric forms (high and low molecular weight and trimeric forms) are assessed using immunoblot analysis.

Androstenedione:  Coated-tube RIA [Diagnostics Systems Laboratories (DSL), Webster, TX]; 50 µl sera, 0.03 ng/ml; intra-assay CV: 1.6%; inter-assay CV: 12.1%.

C-peptide:  Double-antibody radioimmunoassay (Diagnostic Products Corporation, Los Angeles, CA); 25 ul sera per test; sensitivity: 0.318 ng/mL; mean intraassay CV: 3.57%; mean interassay CV: 5.59%.  

Corticosterone: Coated-tube RIA (Diagnostics Products Corp., (DPC), Los Angeles, CA) 50 ul sera; 0.03 ng/ml; intra-assay CV: 1.6%; inter-assay CV: 2.64%.

Cortisol:  Coated-tube RIA (DPC); 25 µl sera; 0.39 µg/dL; intra-assay CV: 5.2%; inter-assay CV:6.8%.

hsCRP: Enzyme Immunoassay (EIA, ALPCO Diagnostics, Salem, NH); 100 µl diluted (1:100) sera; 0.124 ng/mL; intra-assay CV: 13%; inter-assay CV: 12.6%.

DHEA-S:  Coated-tube RIA (DPC) 100 µl sera; 4.95 ng/ml; intra-assay CV: 3.2%; inter-assay CV: 4.1%.

Estradiol:  Double-antibody RIA (DPC); 200 µl sera; 2.15 pg/ml; intra-assay CV: 5.3%; inter-assay CV: 6.0%.

GIP, total (1-42): EIA (Linco);  20µl  sera; 8.2 pg/mL; intra-assay CV: 4.5%; interassay CV: 7.2%

GLP-1  (active): EIA (Linco); 100µl sera; 2 pmol/L; intra-assay CV: 7.4%; interassay CV: 10.7%

Glucagon: Double-antibody RIA (Linco/Millipore, St. Charles, MO); 100 ul sera; sensitivity: 23 pg/ml; intra-assay CV: 4.24%; inter-assay CV: 8.53%.

Insulin: Iimmunoenzymetric assay (TOSOH analyzer); 50 µl sera; 1.0 µIU/ml; intra-assay CV:5.32%; interassay CV:5.52%.  

Insulin (rodent): Double-antibody RIA (Linco; 20 µl sera; 0.06 ng/ml; intra-assay CV: 2.7%; inter-assay CV: 7.3%.

IGF-1: Immunoradiometric assay (IRMA, DSL); 20 µl; 5.7 ng/ml; intra-assay CV: 3.7%; interassay CV: 7.3%.

IGFBP-1: IRMA (DSL); 25 µl sera; 0.18 ng/ml; intra-assay CV: 5.93%; interassay CV: 4.02%.

IGFBP-3: IRMA (DSL); 50 µl sera; 0.5 ng/ml; intra-assay CV: 4.0%; interassay CV: 7.7%.

hsIL-6: EIA (R&D Systems, Minneapolis); 100µL; 0.156 pg/mL; intra-assay CV: 12%; inter-assay CV: 14.5%.

Leptin: Double-antibody RIA (Linco); 100 µl sera; 0.4 ng/ml; intra-assay CV: 5.0%; inter-assay CV: 6.0%.

Sex hormone binding globulin:  IRMA (DSL); 10 µl diluted sera (1:101); 3 nmol/L; intra-assay CV: 4.65%; inter-assay CV: 8.2%.

Testosterone:  Coated-tube RIA (DPC); 50 ul sera; 12 ng/dL; intra-assay CV: 7.7%; inter-assay CV: 8.2%.

Free testosterone (pmol/L): calculated from serum concentrations of total testosterone and SHBG using an algorithm.  This method is based on the concentration of albumin, the binding capacity of SHBG, and the association constants of testosterone for SHBG and albumin, as determined in a sample of normal men and women.  

TNFa: EIA (R&D Systems, Minneapolis); 200µL sera; 0.5 pg/mL; intra-assay CV: 9.0%; inter-assay CV: 19.0%.

sTNFRI: EIA (Biosource, Camarillo, CA); 50µL sera; 50 pg/mL; intra-assay CV: 5%; inter-assay CV: 6%.

sTNFRII: EIA (Biosource); 50µL sera; 0.1 ng/mL; intra-assay CV: 4%; inter-assay CV: 6%.

Other assays available (not conducted routinely, but available on a per-need basis): rodent leptin, rodent adiponectin, rodent IGF-1, estrone, progesterone, prolactin, LH, FSH.

B.     Glucose and lipids: Glucose, total cholesterol, HDL-cholesterol (HDL-C), LDL-C, triglycerides (TG), and total free fatty acids (FFA) are measured in 12 µl sera using a SIRRUS analyzer (Stanbio Laboratory, Boerne, TX).