Seasonal and biological variation of blood concentrations of total cholesterol, dehydroepiandrosterone sulfate, hemoglobin A(1c), IgA, prolactin, and free testosterone in healthy women.

Author(s): Garde AH, Hansen AM, Skovgaard LT, Christensen JM

Publication: Clin Chem, 2000, Vol. 46, Page 551-9

PubMed ID: 10759480 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of time of biospecimen collection on the levels of cholesterol, DHEA-S, IgA, prolactin, and free testosterone in serum and hemoglobin A1C in blood specimens from healthy women. Specimens were collected monthly over the course of 1 year from 11 women, weekly during 1 month from 11 women, and 6 times during 1 day from 10 women. Serum was frozen at -20 degrees C until analysis. Cholesterol, DHEA-S, and IgA were assayed within 6 weeks, while hemoglobin A1C, prolactin, and free testosterone were assayed within 2 months of collection.

   Summary of Findings:

   Hemoglobin A1C and DHEA-S concentrations showed seasonal variations (2 peaks throughout the year), each with higher concentrations roughly corresponding to spring and fall and lower concentrations in summer and winter. Total cholesterol, prolactin, and free testosterone concentrations showed cyclical variations throughout the year (1 peak throughout the year), peaking in winter, spring, and summer, respectively. Peak-trough concentration differences were 12% for cholesterol, 9% for DHEA-S, 7% for hemoglobin A1C, 44% for prolactin, and 31% for free testosterone. IgA concentrations were not significantly affected by month/season of collection. Prolactin and free testosterone levels were significantly higher in the morning, but time of day of collection did not significantly affect DHEA-S or IgA concentrations, however, IgA showed an insignificant trend towards decreasing during the day. Total cholesterol concentrations throughout one day were not examined. Within subject variation during one month amounted to 15% for total cholesterol, 16% for DHEA-S, 3% for the ratio of hemoglobin A1C/total hemoglobin, 16% for IgA, 40% for prolactin, and 64% for testosterone concentrations. These numbers, as well as variance components, were published as an erratum in the October 2001 issue of Clinical Chemistry.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Serum

   Preservative Types

   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Steroid	Clinical chemistry/auto analyzer
   Glycoprotein	Clinical chemistry/auto analyzer
   Protein	HPLC
   Steroid	Immunoassay
   Steroid	Radioimmunoassay
   Peptide	Radioimmunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Time of biospecimen collection	January February March April May June July August September October November December Week 1 Week 2 Week 3 Week 4 9:00-10:00 am (morning) 12:00-2:00 pm (midday) 3:00-5:00 pm (afternoon)

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