Severe Rhabdomyolysis and Acute Renal Failure Due to Noncompliance to Levothyroxine Therapy

Background: Noncompliance to levothyroxine (LT4) is common however only rarely it leads to severe side effects. We report a case of rhabdomyolysis leading to acute kidney injury (AKI) requiring hemodialysis (HD) due to noncompliance to LT4 therapy for one month. Clinical Case: A 68-year-old Caucasian male presented with a 2-week history of worsening fatigue and generalized weakness, accompanied by pain in bilateral lower extremities. Medical history included coronary artery disease, heart failure with reduced ejection fraction, hypertension, dyslipidemia, hypothyroidism, type 2 diabetes mellitus, CKD. Home medications included LT4 200 mcg daily, metoprolol 25 mg daily, doxazosin 2 mg daily, amlodipine 5 mg daily, fluocinonide 40 mg daily, fosinopril 40 mg twice daily, metformin 500 mg twice daily and rosuvastatin 40 mg daily. Further history revealed the patient to be not taking LT4 as “he ran out of it for a month” and only resumed taking it 3 to 4 days before coming to the hospital. On examination, he had proximal muscle weakness with power 3/5 in bilateral lower extremities and mild tenderness on thigh muscles. Labs revealed creatinine 13.1 mg/dL (0.60-1.10 mg/dL), BUN 101 mg/dL (0-30 ng/dL), eGFR 4.0 ml/min/1.73m2, CK 69,500 U/L (22-198 U/L), TSH 55.8 uIU/ml (0.45-4.5 uIU/ml), and FT4 0.61 ug/dL (0.8-1.8 ug/dL). ABG showed metabolic acidosis. Routine labs three months prior revealed normal thyroid function tests (TSH 1.6 uIU/ml and FT4 1.3 ug/dL) on LT4 200 mcg and baseline CKD stage 3b (EGFR 51 ml/min/1.73m2 with baseline creatinine 1.4 mg/dL). The patient was diagnosed with severe rhabdomyolysis secondary to noncompliance with LT4 therapy in presence of concurrent statin use, leading to AKI. Rosuvastatin was stopped and he was treated with aggressive intravenous hydration, sodium bicarbonate, and LT4 200 mcg daily. Despite two days of aggressive treatment, CK remains elevated and hence HD was initiated. The patient underwent three sessions of HD during the course of his hospitalization. Due to lack of renal recovery, outpatient HD was arranged. At 4 weeks of outpatient follow-up, the patient was oliguric and HD dependent. At 8 weeks outpatient follow up, CK, TSH, and FT4 was normal on LT4 200 mcg daily and became dialysis independent. Conclusion: Noncompliance to LT4 therapy along with concomitant use of statin can result in severe rhabdomyolysis induced AKI in patients with CKD.