Serum Ferritin–TSH Ratio as a Novel Biomarker for Symptom Severity in Hypothyroidism

Abstract

Background Hypothyroidism can be biochemically identified as the state of thyroid gland dysfunction that exhibits an, often less-than-ideal correlation between its degree and TSH levels along with symptomatic burden. In thyroidal hormone production and metabolism, the iron status may be used in order to determine variations between them. Objectives To correlate the iron store, which may be measured as serum ferritin, TSH, and the Ferritin/TSH ratio with disease symptoms experienced by primary hypothyroid patients. Methods Cross-sectionally, from the outpatient clinics of endocrine and internal medicine,72 patients with proven primary hypothyroidism were selected over 4 months, within a teaching hospital at an urban city located in the province of Sindh of Pakistan. Severity was assessed with the Hypothyroid symptom Scale(HSS),TSH/FT4 was quantified using chemiluminescent immunoassay while ferritin usedELISA. Results Pearsons correlation coefficient and studentt-test were conducted. Mean age of participants were 39.6 ± 10.8 yrs; 52 (72.2%) were women. Ferritin positively correlated to symptom Burden of HSS (r=−0.41;95%CI −0.59 to −0.20; P<0.001),and TSH showed a directly proportional correlation (r=0.46,95%CI 0.26 to0.63; P<0.001) with HSS. The ratio of Ferritin:TSH yielded the strongest correlations with HSS (r=0.58, 95%CI 0.40 to 0.72;P<0.001) . Those scoring more than 18 in HSS had the lower Fer:TSH value when compared to those scoring18 orbelow(3.5±1.6 versus 6.1 ± 2.4; P<0.001). Conclusion A low Ferritin:TSH value correlates with a significant increase in symptom intensity in primary hypothyroidism, and showed a higher association than either TSH or ferritin individually with HSS scores, prior to adjusted and cross-sectional studies and longitudinal validity; it’s value can not be recommended bedside use