Annals of Thyroid Research
Thyroid Stimulating Hormone (TSH) alone is often used as
a primary marker to screen for thyroid function. Significant intra-individual
variation of TSH concentrations occur in healthy individuals. Intra-individual sex
and time-based variations pose the question of whether TSH can reliably screen
for thyroid disorders.
Objective: To quantify the degree of diurnal fluctuations in TSH
concentrations of healthy individuals and assess its diagnostic reliability. To
propose preliminary sex and time dependent TSH reference intervals.
Design and Methods: Healthy volunteers (n=102) were recruited from
4 participating sites. Couplet (AM and PM) serum samples were drawn and
analyzed for TSH concentration using immunoassay.
Results: Significant AM to PM increases in TSH levels for both men (P <
0.0001) and women (P = 0.0003) were noted.
Conclusion: TSH should not be used as a single marker for the assessment
of thyroid function. We recommend that TSH be used in conjunction with Free
Thyroxine (FT4), Free Triiodothyronine (FT3), and Total T3 measured by LCMS/
Keywords: Thyroid stimulating hormone; Congenital hypothyroidism;
Immunoassays; Thyroid function
Highlights: Significant differences exist in:
1. Intra-individual TSH concentrations
2. Diurnal and sex-based TSH concentrations
1 and 2 together with the many drugs and steroids that lower TSH
concentrations, suggest we should question the reliability of TSH as a
single marker of thyroid function.
TSH Should not be used as a Single Marker of Thyroid
Sheikh S, Parikh TP, Kushchayeva Y, Stolze
B, Masika LS, Ozarda Y, Jonklaas J, Nigussie
G, Remaley AT, Sampson