Endocrine Abstracts

We measured chromogranin A (CgA) and chromogranin B (CgB) in 36 patients, recently confirmed to have a midgut carcinoid tumour (MGC), prior to the commencement of octreotide treatment. Blood samples were taken before and after a bolus injection of 50 μg octreotide. There were 21 males, 15 females, age range 28–76 median 61 years.

Basal CgA, expressed as times the upper limit of normal (ULN) ranged from 333.3 to 0.5 ULN. Basal CgB ranged from 33.7 ULN to zero (undetectable). Of 36 patients, 21 had highly elevated basal CGA (> X5 ULN), ten had moderately elevated CGA (X2–X5 ULN) and five patients had normal or marginally raised CgA. Nine patients had CgB > X2 ULN, four patients had elevated CgB up to X2 ULN and 23 had normal CGB. All patients with elevated CgB also had raised CgA. Fourteen of 29 patients with raised basal CgA showed a significant (>20%) decrease in CgA 60 min after octreotide injection. Three showed an increase of >20%. The remaining patients showed no significant change. Seven of 11 patients with a high basal CgB showed a decrease >20% 60 min post injection.

It is generally observed that very high CgA concentrations before treatment begins may indicate advanced stage of disease and therefore poor prognosis. A lack of response may also predict a poor prognosis. However, good biochemical response to bolus octreotide may indicate a good future response to treatment. CgB was performed to assess its usefulness as a supplementary diagnostic test in neuroendocrine tumour patients with normal CgA. We did not observe any patients with raised CgB only according to the supplied kit reference range.