Q: My 66-year-old father is suffering from hypothyroidism. What is the ideal dose of Eltroxin for him? His TSH is 22 uIU/ml and T4 is 3 ng/dl. I have read on the Internet that older people need a lesser dose than young people. Should it be 25 mcg/day or 50 mcg/day or 100 mcg/day? He is also suffering from a complete loss of appetite and low blood pressure (90/60 mmHg}. His serum sodium is 129 mmol/L and potassium is 3.91 mmol/L.

A:The dose of thyroxine depends upon the age and weight of the patient. In children, the dose is much higher as compared to adults. The adult dose is 1.8 ug/kg/d. But in elderly, we start with a small dose, i.e., 25 ug/d and increase slowly over a span of 4-6 weeks time. For your father, I suggest that you start with a dose of 25/d and after 15 days increase it to 50/d. Then get a repeat TSH after six weeks. If it is in normal range, then continue with the same dose. If it is still high, then increase it to 75/d. But we have to be cautious in your father's case as his BP is on the lower side and his Na is also low. In addition, I suspect he has cortisol deficiency, which can be tested by doing an 8.00 AM cortisol level.