Download TSH, Ultrasensitive

TSH, Ultrasensitive
8660X
Clinical Use
• Diagnose hypo- and hyperthyroidism
• Monitor T4-replacement or T4suppressive therapy
• Quantify TSH levels in the subnormal range
Reference Range
Adults
Men and nonpregnant women
Pregnant women
1st trimester
2nd trimester
3rd trimester
Children
1-4 d
5-6 d
1-4 wk
1-12 mo
1-19 y
mU/L
0.40-4.50
0.30-4.50
0.50-4.60
0.80-5.20
3.20-35.00
Not established*
1.70-9.10
0.80-8.20
0.50-4.30
*TSH levels decline rapidly during the
first week of life in most children, but
may remain transiently elevated in a few
individuals despite normal free T4 levels.
For confirmatory testing following a
newborn thyroid screen, a free (or total)
T4 level is usually required for proper
interpretation of TSH levels in this age
group.
Interpretive Information
• Primary hypothyroidism
• Decreased thyroid reserve
(sub-clinical hypothyroidism)
• TSH-dependent hyperthyroidism
• Thyroid hormone resistance
Clinical Background
The serum TSH measurement is
1 of the most important tools in the
diagnosis of thyroid disorders. TSH
secretion from the pituitary gland is
controlled by hypothalamic TRH
and a negative feedback effect from
circulating, free thyroid hormones.
Thus, in subjects with a normal
hypothalamic-pituitary system, there
is an inverse correlation between
free thyroid hormone and TSH
concentrations in serum. Increased
serum TSH is an early and sensitive
indicator of decreased thyroid reserve
and overt primary hypothyroidism.
A third-generation TSH assay using
chemiluminescent technology
produces functional sensitivities of
0.01 mU/L, permitting reliable
quantification of serum TSH concentrations in the subnormal range. This
allows differentiation of euthyroid
from hyperthyroid patients. This
assay also helps diagnose essentially
all patients with TSH-independent
hyperthyroidism (Graves disease,
etc.) with a single blood sample. In
addition, the assay allows adjustment
of exogenous thyroxine dosage in
hypothyroid patients and in patients
on suppressive thyroxine therapy for
thyroid neoplasia.
Method
• Immunochemiluminometric assay
(ICMA)
• Analytical sensitivity: 0.01 mU/L
Specimen Requirements
2 mL refrigerated serum (no additive
red top tube); 0.5 mL minimum
• Graves disease
• Autonomous thyroid hormone
secretion
• TSH deficiency
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