The significance of high thyroxine in hospitalized patients with low thyroid-stimulating hormone

Subclinical hypothyroidism or isolated high TSH in hospitalized patients with chronic heart-failure and chronic renal-failure

Sub-clinical hypothyroidism (SCH) is common in heart failure (HF) and advanced renal failure (RF), but it is unclear whether there is a thyroid disease or a transient increase in TSH level. This is a retrospective study of hospitalized patients in medical departments. All patients with SCH and a TSH level up to less than 12 mIU/L were identified. Those who had at least one recurring admission within at least 6 months were included. A change in thyroid function during the last re-admission was determined and classified as an improvement, no change, or worsening of thyroid function. Overall, 126 cases of SCH met the inclusion criteria for re-admission. Analysis of the most recent hospitalization showed that in 100 (79.4%) patients thyroid function improved, in 15 (11.9%) patients thyroid function remained unchanged and only in 11 (8.7%) patients did thyroid function worsen. In most cases, worsening of hypothyroidism was determined by initiation of a low dose levothyroxine treatment. Of the 126 participants, 43 (34.1%) and 22 (17.5%) had a diagnosis of HF and RF (CKD stages 4 and 5), respectively. There was no association between HF or advanced RF and worsening of SCH. No association was found between worsening of hypothyroidism and gender, age, TSH, or creatinine levels in the first hospitalization. A borderline association between elevated CRP levels at first hospitalization and hypothyroidism worsening was found (p = 0.066). Mildly elevated TSH in hospitalized patients with HF and advanced RF is transient and most probably not related to thyroid disease and not associated with age or gender.