Isolated ACTH deficiency presenting twenty two years after radiotherapy for nasopharyngeal carcinoma
Senthil Rajasekaran & Jimmy SW LI Voon Chong
A 67 y old man was brought to the A & E department after being found unresponsive. He was drowsy, hypotensive (BP 90/ 60 mmHg) and had low blood glucose of 1.2 mmol/L. Serum Na was 126 mmol/l (135145) and K 3.5 mmol/L (3.55.0). CXR showed a left basal consolidation. Intravenous 10% dextrose and antibiotics were given. Twenty two years prior, he was diagnosed with squamous cell carcinoma of nasal septum associated with nodal involvement in the neck. He underwent radical neck dissection followed by radiotherapy.
Short synacthen test showed cortisol deficiency (Cortisol 37 nmol/L at time 0 mins, 103 nmol/L at 30 mins and 142 nmol/L at 60 mins). Serum ACTH level was <5 thereby indicating secondary hypocortisolism. MRI of the pituitary gland was normal. Thyroid function tests initially showed a low free T4 7.7 pmol/L (1222) and a high TSH of 8.16 mU/L which normalized after two months without any thyroxine therapy. Glucagon stimulation test showed normal growth hormone reserve (max GH of 39 mU/L). Serum Prolactin, FSH, LH and Testosterone levels were normal.
He made a good recovery with oral hydrocortisone replacement therapy.
This illustrates a rare case of isolated ACTH deficiency presenting twenty two years after radiotherapy for nasopharyngeal carcinoma. Long term regular endocrine assessments should be carried out in those patients.