Endocrine Abstracts

A 31-year-old Caucasian male with chronic fatigue syndrome and additional symptoms of abdominal pain and diarrhoea, was referred by his neuro-gastroenterologist for investigation of possible carcinoid tumour after finding a raised 24 h urinary 5HIAA level – 220 μmol/24 h (normal range <50 μmol/24 h).

Full blood count, urea and electrolytes, liver function tests, plasma and urinary catecholamines were all within normal range.

A CT of the chest, abdomen and pelvis had detected no tumour.

A detailed history revealed that the patient had become disillusioned with conventional medical therapy for his Chronic Fatigue and had seen a nutritionist in the alternative healthcare sector.

He had been ‘prescribed’ a large number of nutritional supplements.

One of these supplements was ‘5HTP’. This is 5-hydroxytryptophan, a precursor of serotonin. A rise in urinary 5HIAA to a median of 204 μmol/24 h with 5HTP ingestion in healthy subjects had previously been observed¹.

The 5HTP tablets were stopped and two weeks later, two repeat 24 h urinary 5HIAA analyses returned within normal limits (13 and 12 μmol/24 h).

This, coupled with an unremarkable CT scan effectively excluded a carcinoid tumor.

It has also been shown² that certain foods elevate urinary 5HIAA. A 1985 paper² demonstrated that foods like walnuts, pecans, plantain and pineapple are especially high in serotonin and their consumption can cause a raised urinary 5HIAA (1 black walnut can cause a rise of 5 μmol/24 h and 1 banana by 10 μmol/24 h)².

This case highlights the importance of alternative medicines and diet as confounding factors in the biochemical investigation of Carcinoid.

References

1. Joy T, Walsh G, Tokmkejian S & Van Uum SH. Increase of urinary 5-hydroxyindoleacetic acid excretion but not serum chromogranin A following over the counter 5-hydroxytryptophan intake. Can J Gastroenterol 2008 22 49–53.

2. Feldman JM & Lee EM. Serotonin content of food: effect on urinary excretion of 5-hydroxyindoleacetic acid. Am J Clin Nutr 1985 42 639–645.