Severe hypothyroidism is known to cause elevation of creatinine and this phenomenon has been reported in clinical settings in the past. Screening for hypothyroidism is not regularly performed in the differential workup for acute kidney injury due to its rare presentation. Therefore, to most physicians hypothyroidism is not known as a cause of acute kidney injury. In this clinical case report, we describe a case of subacute kidney injury in a patient with severe hypothyroidism prior to iodine-131 ablation therapy. Hypothyroidism was not recognized as the cause of elevated creatinine, which in this case led to unnecessary hospital admission and diagnostics. This case report serves as a reminder for clinicians to consider hypothyroidism in the differential diagnosis of (sub)acute kidney injury.