Endocrine Abstracts

Although amyloid deposition can cause a goitre thyrotoxicosis secondary to amyloidosis is rare. We report a case of fatal systemic amyloidosis presenting as thyrotoxicosis.

A 62-year-old previously healthy male presented with heat intolerance, weight loss and tremor. On examination he had moderate sized firm goitre and mild dysthyroid eye disease. Biochemistry confirmed thyrotoxicosis; serum free T4 47 pmol/l (normal 10–25) freeT3 14.4 pmol/l (normal 2.5–6.6) and TSH<0.01 mU/l (normal 0.3–5.5). He had no family history of thyroid disease and thyroid antibodies were negative. A technetium scan showed evenly distributed activity throughout the gland. He was commenced on block and replace therapy. Thyroid function tests normalised and the patients’ symptoms improved.

Because of the bulky goitre and thyroid eye disease a thyroidectomy was performed and histology demonstrated extensive amyloid deposition throughout the thyroid gland. Thyroxine replacement was required. Further investigations revealed no evidence of myeloma with a normal skeletal survey, normal serum electrophoresis, 10% plasma cells in the bone marrow and normal bone marrow trephine. However his serum free light chain sample showed a heavy kappa predominance (kappa 338 mg/l, lambda 25.5 mg/l ratio 13.3). A rectal biopsy did not show amyloid on congo red staining. He developed progressive lethargy and peripheral oedema and investigation revealed anaemia (Hb 88 g/l) and nephrotic syndrome (24 hr urine protein 4.9 grams).

The patient was reviewed at the National Amyloidosis Centre and a SAP scan demonstrated moderate to large amyloid load in the liver, spleen, kidneys and bone marrow, the last of these being pathognomonic of AL amyloidosis. Reduced dose melphalan chemotherapy was instigated. One week later he suffered a severe GI haemorrhage and endoscopies demonstrated multiple petechial lesions throughout the GI tract, he subsequently developed pancytopenia and was supported actively with blood products. He became increasingly unwell and died 18 months after the diagnosis of thyrotoxicosis had been made.