Thyrotoxicosis with osteomalacia and proximal myopathy

A 36 year old lady, presented with symptoms of proximal myopathy was found to have a history of thyrotoxicosis for which she had taken carbimazole irregularly for 1-1/2 years. On admission, clinical signs of thyrotoxicosis were detected and confirmed by estimating serum T3 and T4. Neurological examination revealed generalised wasting, loss of power in the proximal muscles with a myopathy confirmed on EMG. Serum calcium, phosphorous levels, and a 24 hour urine calcium excretion were low. Alkaline phosphatase levels were high. A diagnosis of thyrotoxicosis with osteomalacia was made. The patient improved within 3 weeks of starting carbimazole and vitamin D.