Serum thyrotropin values in nearly 1000
normal adults varied no more than in smaller groups
(November 2004)
The background of the study. Measurement of serum
thyrotropin (TSH) is the best test of thyroid dysfunction, but there
has been debate about the definition of the normal reference range.
This study was done to define the normal range for serum TSH in
carefully selected normal subjects.
How the study was done. The study group consisted
of self-reported healthy subjects, aged 17 to 66 years, who were
recruited from a cohort of monozygotic and dizygotic same- and opposite-sex
twin pairs. Among them, 90 were taking some medication, 105 had
a family history of thyroid disease; 129 had high serum concentrations
of antithyroid peroxidase (anti-TPO) antibodies, antithyroglobulin
(anti-Tg) antibodies, or TSH-receptor (TSHR) antibodies; 87 had
high serum concentrations of two or three of the antibodies; 34
had a family history of thyroid disease and a high serum concentration
of one or more of the antibodies; and 987 (460 women, 527 men) had
none of these characteristics.
The results of the study. The reference interval
for the 987 subjects with no risk factors for thyroid disease was
0.58 to 4.1 mU/L (95 percent confidence interval, 0.55 to 0.61 mU/L
for the lower limit, and 3.8 to 4.2 mU/L for the upper limit). The
distribution of the values in the women and men and in the different
types of twin pairs was similar to that in all the subjects. The
distribution of the values was skewed to lower values in the 105
subjects with a family history of thyroid disease, and that in the
76 subjects with high serum anti-TPO antibody values was skewed
to higher values.
The conclusions of the study. Serum TSH concentrations
in a large group of normal adult men and women ranged from 0.58
to 4.1 mU/L, similar to the reference ranges based on results from
fewer, less carefully selected subjects.
The original article. Jensen E, Hyltoft Petersen
P, Blaabjerg O, Hansen PS, Brix TH, Kyvik KO, Hegedus L. Establishment
of a serum thyroid stimulating hormone (TSH) reference interval
in healthy adults: the importance of environmental factors, including
thyroid antibodies. Clin Chem Lab Med 2004;42:824-32.
|
