Case Report/Case Presentation
Our case is 35 years old female known to have type 2 Diabetes Mellitus on metformin 1 gm daily. In 2014, the patient presented with fatigue and weight gain. Work up showed TSH 23 Miu/l (0.5 to 5.5 Miu/l) and T4 of 15 Miu/l (9 to 21 Miu/l). The patient was diagnosed with subclinical hypothyroidism and started on levothyroxine treatment. Starting dose was 25 mcg daily and the patient was followed to monitor her symptoms and TSH level.
In next follow up appointments, the patient reported some improvement in her symptoms. however, her TSH level was persistently elevated. Thyroxin dose was gradually built up till a dose of 100 mcg was reached over 4 years period but TSH level wasn’t inhibited. Other labs including complete blood count, renal function, liver function and lipid profile were within normal limits.
Appointment in November 2018, TSH was 20 miu/L. levothyroxine dose was subsequently increased to 150 mcg daily. Few weeks later, the patient reported hyperthyroid symptoms including insomnia, tremors and palpitation. Repeated thyroid function test showed TSH of 6.6 miu/L and T4 level was significantly high (30 mic/L). the dose was reduced to 100 mcg and antibodies were requested.
Next appointment following reduction of levothyroxine dose, her insomnia and palpitations improved. Repeated labs showed TSH 34 miu/L, T4 17 miu/L, antithyroid peroxidase antibody > 600 IU/ml (0 to 34 IU/ml), antithyroglobin antibody 489 IU/ml (0 to 115 IU/ml) and TSH receptor antibody 0.8 IU/L (0 to 1.7 IU/L).Figure 1 showed TSH, T4 and T3 throughout treatment with various doses of levothyroxine from time of diagnosis ( 2013) till 2020,