A 13-year-old previously healthy male presented 8 weeks after his initial diagnosis of COVID-19 infection to his pediatrician with complaints of dizziness, fatigue, difficulty sleeping, and a presyncopal episode. The patient was unable to participate in daily activities without getting easily fatigued. Parents reported increased appetite but still a documented weight loss of 8 lbs (5.3% bodyweight) since his COVID-19 illness over a period of 2 months. Further review of system revealed significant heat intolerance requiring multiple fans pointed at him while sleeping without any covers. He also had an itchy groin rash for which he was using topical cotrimoxazole cream with some improvement. He denied any sexual activity or illicit drug use. He was diagnosed with COVID-19 on a nasal PCR test 8 weeks prior to current presentation. He had a mild course with low-grade fever, congestion, cough, and body aches that resolved in few days. All family members were positive at the same time with his father requiring a three-week hospital stay for COVID-19 pneumonia. Other than his recent COVID-19 illness, he had no significant past medical history. He was born in Mexico and had immigrated to the United States three years ago. His immunizations were up to date. Family history was negative for any rheumatological or autoimmune disorders. He was at 98th percentile for height and 93rd percentile for weight with a BMI of 81st percentile for age. Examination was significant for tachycardia at 102 beats per minute with mild exophthalmos and palpable thyroid. He had an erythematous lesion in intertriginous left groin. His electrocardiogram showed sinus tachycardia. Results of initial blood work revealed elevated free T4 at 2.5 ng/dL (normal range: 0.7-1.5 NG/DL), undetectable TSH at <0.01 uIU/mL (normal range 0.50-4.80 uIU/mL), normal complete blood count, normal sedimentation rate, and a negative QuantiFERON TB gold test. Further workup showed elevated antithyroid peroxidase (TPO) antibodies at 946.2 IU/ml (normal <9.0 IU/ML) and elevated thyroid-stimulating immunoglobulins (TSIs) at 28.2 IU/L (normal <0.10 IU/L). Given the presence of antibodies for both Graves and Hashimoto's (with TSI predominance), he was diagnosed with hyperthyroidism from autoimmune thyroid disease. He was started on methimazole 10 mg once daily at that time. At 2-month follow-up, he had some symptomatic improvement in his energy levels with some weight gain, but still had palpitations and difficulty sleeping with some heat intolerance. Propranolol 10 mg twice daily was added for symptomatic relief. He also reported worsening of his groin rash despite changing to different antifungal creams. Upon dermatology consultation, he was determined to have psoriasis vulgaris and was treated with topical steroids resulting in complete resolution.
At 4-month follow-up, he showed biochemical improvement while on thionamide therapy, as his free T4 had normalized to 1.2 ng/dl, but his TSH remained at < 0.01 uIU/ml. However, he clinically continued to have mixed thyroid symptomology with fatigue, weight gain, poor concentration, insomnia, depression/anxiety, heat intolerance, and palpitations. This reiterates that long COVID-19 may persist in some long haulers even after other medical conditions are controlled.