Endocrine hypofunction as a consequence of metastatic cancer
R Srinivasan, J Flood, SM Thomas, AL Brackenridge, PV Carroll & JK Powrie
Introduction: Endocrine deficiency as a result of glandular infiltration by metastatic cancer is considered rare. Metastases to the adrenal cortex are relatively common and we present the clinical presentation and radiological appearances of cases involving pituitary and adrenal metastases.
Case histories: Case 1: An 84 year old male with bronchogenic carcinoma presented with lethargy, polyuria and dehydration. The serum Na+ was 156 mmol/L with urinary osmolality of 106 mOsm/kg and there was TSH, ACTH, LH/FSH and GH deficiency. MRI showed hypothalamic metastasis with probable pial spread.
Case 2: A 59 year old lady with established breast carcinoma presented with headache, dizziness, polyuria and polydipsia. MRI showed prominent enlargement and enhancement of pituitary stalk due to metastasis. Biochemical investigation confirmed pan-hypopituitarism and diabetes insipidus.
Case 3: This 63 year old man who had CT abdomen for staging of lung primary was found to have bilateral adrenal metastases. The following results were obtained: serum Na+143 mmol/L; Cortisol levels at baseline and following 250 μg synacthen® were199 & 240 nmol/L respectively. Aldosterone <70 pmol/L and renin was 4.8 (0.53.1 p/mL/H). These results confirmed primary hypoadrenalism and replacement medication was commenced.
Discussion: As was the case in the first 2 patients pituitary region metastases commonly present with diabetes insipidus. The posterior pituitary is the preferred site of metastases possibly as a result of the blood supply to the gland. Pituitary stalk metastases can also lead to hypopituitarism and may be visible only as stalk thickening in the MRI scan. It is considered that >90% of the adrenal cortex must be destroyed before hypoadrenalism occurs, but partial adrenal insufficiency may be seen in bilateral adrenal involvement by metastases. Pituitary and adrenal insufficiency should be considered in metastatic cancer as endocrine hypofunction may worsen prognosis and reduce the quality of life in these patients.