Endocrine Abstracts

Introduction: Despite hypothyroidism being seen in patients with kidney disease, it is rarely the underlying cause. We present a rare case of chronic kidney disease (CKD) secondary to severe hypothyroidism that was totally reversed on commencement of Levothyroxine. The mechanism is multifactorial, and importantly involves the pre-renal and direct renal effects of thyroid hormones.

Case report: A 37-year-old Caucasian male presented to the endocrine clinic in March 2020 after a GP friend mentioned that he did not look well. The patient did not feel unwell himself, however on direct questioning complained of cold intolerance, fatigue, puffy eyelids, and weight gain over the preceding years. Most notable to the patient was hair loss on the body and scalp which had left him bald. The patient’s history was only significant for gout. Blood tests showed TSH 548.7 (0.27-4.2) and Free T4 undetectable <4 (12-22). The thyroid antibodies were within normal range. He was 89.95 kg with a BMI in the obesity range (31.12). Additionally, the patient had asymptomatic CKD seen by metabolic abnormalities in the blood test: normocytic anaemia with haemoglobin 87 (130-175), urea 9.3 (2.1-8.5), creatinine 150 (65-119) and GFR 46 (>90). On examination, he had puffy eyelids, but no evidence of goitre. Systemic cardiovascular, respiratory, and abdominal examinations were unremarkable. A thyroid ultrasound showed a small thyroid gland with benign changes suggestive of chronic thyroiditis. He was diagnosed with primary hypothyroidism and commenced on 150μg Levothyroxine once daily. Within two months of starting Levothyroxine, kidney function improved to a GFR of 88. At present, patient is taking 100μg of Levothyroxine once a day, with normal thyroid function tests and normal kidney function. The patient has marked regrowth of scalp hair and has had a significant weight loss of 15.75 kg.

Conclsion: Despite being commonly encountered and well understood individually, hypothyroidism is an underappreciated reversible cause of renal impairment and the interaction between thyroid hormones and the kidneys are rarely remembered. Patients can be asymptomatic even with severe hypothyroidism and CKD; the treatment is sufficient replacement with Levothyroxine which can show profound kidney improvement − as with our patient this can happen within only two months. Hence, clinicians should ensure that renal function tests be performed on initial diagnosis of hypothyroidism to ensure that this reversible complication can be adequately managed with Levothyroxine.