An Elderly Woman with Pyrexia of Unknown Origin.

Pyrexia of unknown origin represents a diagnostic challenge in the daily practice. Clinical features are often subtle or inadequate to recognize the etiology of prolonged fever. Endocrine etiology of pyrexia of unknown origin is not common. Here we present a case of an elderly female seeking medical advice from her general practitioner due to a four-week history of moderate fever, malaise and loss of appetite. Initial outpatient diagnostic workup was negative. During repeated examination a slight enlargement of thyroid gland was noticed. Thyroid function tests revealed a very low level of thyroid stimulated hormone along with elevated free T4 suggesting subacute thyroiditis. Low dose administration of corticosteroids led to clinical improvement and fever remission. Physicians involved must be aware about this unusual presentation of thyroiditis and include the condition in the differential diagnosis of prolonged unexplained fever. In the absence of clinical signs and symptoms, an abnormal thyroid function test may prevent from unnecessary investigations and inefficient hospital admission.