Variations in thyroid stimulating hormone levels in various non-thyroidal illnesses

ABSTRACT

To find out the pattern of variations in thyroid stimulating hormone [TSH] levels in hospitalized patients with major Non-Thyroidal Illnesses [NTIs] leading to stressful state. A cross-sectional study was carried out in the Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology [AFIP] and the Department of Pathology, Army Medical College Rawalpindi in collaboration with Department of Internal Medicine MH, Rawalpindi. Two hundred patients, were selected by convenience sampling, who were suffering from acute febrile illness, acute psychiatric illness, acute myocardial infarction and surgical trauma [50 each]. Fifty age and sex matched subjects without present or previous history of thyroid disorders were also included as controls to neutralise the confounding variables affecting TSH estimation. Serum TSH, triidothyronine [T[3] and free tetraidothyronine [fT[4] were measured during the course of these illnesses and after complete recovery. Serum TSH, T[3] and fT[4] were estimated in the laboratory by chemiluminescence method using auto-analysers lmmulite-2000 [DPC-USA] and LIA-Mat [Sangtech-Germany] at AFIP and Army Medical College, respectively. Tests related to the concurrent illnesses e.g. liver and renal function tests and cardiac enzymes were assayed by routine end-point and kinetic methods using commercial kits manufactured by M/S Linear Chemicals [Spain] on Selectra 2 Chemistry Auto-analyser. [Mecrk-Germany]. In patients of acute febrile illness there was no statistically significant difference in serum TSH levels in patients [mean 2.03 mlU/L] and control group [mean 1.99 mlU/L] [P>0.05]. Serum TSH was significantly higher in patients of surgical trauma [mean 3.87 mlU/L [J/L] acute myocardial infarction [mean 5.55 mlU/L] and in patients with acute psychiatric illness [mean 3.94 mlU/L] as compared to controls [P<0.05]. The transient abnormalities in serum TSH levels can mimic or at times mask the biochemical changes observed in patients with intrinsic thyroid disease, so realisation and recognition of these responses help in avoiding misdiagnosis