Letters to the Editor
What Is the Clinical Validity of TSH Levels?
Am Fam Physician. 2002 Jul 15;66(2) Online.
to the editor: I enjoyed the excellent review, entitled "Treatment of Hypothyroidism."1 However, the article does not address the issue of the clinical validity of thyrotropin-stimulating hormone (TSH) levels in patients recovering from major illness. It is known that TSH production is suppressed in severely ill patients and that there may be a temporary rebound to above-normal levels during convalescence. What does this say about the reliability of TSH results obtained shortly before or shortly after the patient is discharged from the hospital?
1. Hueston WJ. Treatment of hypothyroidism. Am Fam Physician 2001;64:1717-24.
in reply: As Dr. Gillette points out, the measurement of thyroid-stimulating hormone (TSH) during episodes of acute illness can be inaccurate in some patients. Investigators have found that acute illness blunts the primary response to TSH, which would account for low TSH values during times of physiologic stress,1 producing falsely depressed TSH levels during illness. However, another group2 found that TSH levels were elevated during acute illness. Finally, a third study3 found both falsely depressed (9 percent of cases) and falsely elevated (4 percent of cases) TSH levels in geriatric patients with acute illness. Any abnormality in TSH obtained during an acute illness should be interpreted cautiously, and the thyroid status of the patient should be reexamined after recovery.
1. Bratusch-Marrain P, Vierhapper H, Grubeck-Loebenstein B, Waldhausl W, Kleinberger G. Pituitary-thyroid dysfunction in severe non-thyroid disease: "low-T4 syndrome." Endorkrinologie 1982;80:207-12.
2. Wong ET, Bradley SG, Schultz AL. Elevations of thyroid-stimulating hormone during acute nontyhroidal illness. Arch Intern Med 1981;141:873-5.
3. Bhakri HL, Fisher R, Khadri A, MacMahon DG. Longitudinal study of thyroid function in acutely ill elderly patients using a sensitive TSH assay-defer testing until recovery. Gerontology 1990;36:140-4.
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