Severe Hyperbilirubinemia Associated With Thyrotoxicosis: Importance of Early Recognition
Abstract Thyroid storm (TS) is a rare and life-threatening condition due to a profound hypermetabolic state, leading to decompensation of homeostasis. It is commonly associated with a precipitating factor such as surgery, trauma, or infection. Occasionally, the clinical presentation may be non-specific, thus causing a potential delay in diagnosis. This could be problematic due to the condition’s high mortality rate, especially if not recognized early. Thyrotoxic jaundice presenting with a pattern of cholestatic hyperbilirubinemia (HBR) has been reported in the literature, although uncommon. We present the case of a 71-year-old woman with unexplained jaundice and direct HBR who was diagnosed with impending TS in the setting of toxic multinodular goiter (TMNG). This is a case of a 71-year-old woman with a remote history of hypothyroidism who presented with acute onset right upper quadrant abdominal pain, jaundice, a non-tender asymmetric nodular large goiter, and bilateral non-pitting leg edema. Ancillaries were significant for total and direct HBR of 4.3 and 3.5 mg/dL, respectively. An abdominal sonogram, abdomen CT and ERCP, all ruled out an obstructive biliary etiology. Unfortunately, the patient developed post-ERCP pancreatitis, with subsequent worsening of direct HBR. TSH was found to be suppressed, free T4 was significantly elevated at 4.3 ng/dL. A Burch-Wartofsky score of >40 was highly suggestive of TS. In addition, elevated thyroglobulin levels ruled out exogenous thyrotoxicosis, the absence of orbitopathy, pretibial myxedema, and negative TRAb pointed towards TMNG as the most likely etiology of hyperthyroidism. This diagnosis was confirmed through neck ultrasound, showing multiple nodules and the absence of high vascularity of the thyroid gland. The patient was managed in the ICU with beta-blockers, methimazole, potassium iodide solution, glucocorticoids, and bile acid sequestrants, leading to satisfactory and significant clinical improvement of thyrotoxicosis and bilirubin levels. Hepatic dysfunction has been described in patients with hyperthyroidism since the nineteenth century. Although the underlying mechanism remains unclear, it may be multifactorial. Different hypotheses have been proposed suggesting that the hypermetabolic state secondary to decompensated hyperthyroidism causes a supply-demand mismatch between hepatic oxygen consumption and hepatic blood flow, decreasing the oxygen tension in the centrilobular region resulting in cholestasis. Furthermore, hepatic hypermetabolism in response to excess thyroid hormone leads to the saturation of the bile flow rate. A possible direct toxic effect of T4 in the hepatocytes has been described although further research is needed. This case highlights the importance of considering decompensated hyperthyroidism as a differential diagnosis of cholestatic HBR.
