The porphyrias are disorders of haem biosynthesis which present with acute neurovisceral attacks or disorders of sun-exposed skin. Acute attacks occur mainly in adults and comprise severe abdominal pain, nausea, vomiting, autonomic disturbance, central nervous system involvement and peripheral motor neuropathy. Cutaneous porphyrias can be acute or chronic presenting at various ages. Timely diagnosis depends on clinical suspicion leading to referral of appropriate samples for screening by reliable biochemical methods. All samples should be protected from light. Investigation for an acute attack: • Porphobilinogen (PBG) quantitation in a random urine sample collected during symptoms. Urine concentration must be assessed by measuring creatinine, and a repeat requested if urine creatinine <2 mmol/L. • Urgent porphobilinogen testing should be available within 24 h of sample receipt at the local laboratory. Urine porphyrin excretion (TUP) should subsequently be measured on this urine. • Urine porphobilinogen should be measured using a validated quantitative ion-exchange resin-based method or LC-MS. • Increased urine porphobilinogen excretion requires confirmatory testing and clinical advice from the National Acute Porphyria Service. • Identification of individual acute porphyrias requires analysis of urine, plasma and faecal porphyrins. Investigation for cutaneous porphyria: • An EDTA blood sample for plasma porphyrin fluorescence emission spectroscopy and random urine sample for TUP. • Whole blood for porphyrin analysis is essential to identify protoporphyria. • Faeces need only be collected, if first-line tests are positive or if clinical symptoms persist. Investigation for latent porphyria or family history: • Contact a specialist porphyria laboratory for advice. Clinical, family details are usually required.

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The biochemical investigation of carcinoid disease has relied on measurement of the daily excretion of 5-hydroxyindoleacetic acid (5-HIAA) in urine.1 Collection of 24-h urine has considerable disadvantages for the patient. Inconvenience, embarrassment, strict dietary requirements and the need for hazardous preservatives make this test unpopular, and signi®cant errors in collection may be made. The measurement of 5-HIAA in plasma would offer a more convenient alternative. However, the value of plasma 5-HIAA measurements in carcinoid disease has not been evaluated. Highperformance liquid chromatographic (HPLC) methods for measuring plasma 5-HIAA have been described previously, but applied to the investigation of patients with psychiatric and neurological disorders. 2 We describe a simple, isocratic HPLC method with¯uorimetric detection following ether extraction of 5-HIAA from plasma. This method was used to determine a reference range for plasma 5-HIAA in normal individuals and to investigate patients with known carcinoid disease. The effect of serotonin-containing foods on plasma 5-HIAA was also evaluated. MATERIALS AND METHODSOne hundred microlitres of internal standard (3´4 mmol/L 5-hydroxyindole-2-carboxylic acid) was added to 0´5 mL of heparinized plasma and diluted with 1 mL of water. The solution was acidi®ed with 25 mL of 50% glacial acetic acid and saturated with 1 g of sodium chloride. Extraction was carried out by shaking with 5 mL of diethylether for 2 min. After centrifugation at 2000 g for 5 min the ether layer was decanted into a glass tube and evaporated to dryness under nitrogen at 398C. The residue was reconstituted with 350 mL of mobile phase 5-HIAA (0´1 mol/L ammonium acetate, pH 4´55, containing 7% acetonitrile). 5-HIAA and the internal standard were separated isocratically on a 4´66250 mm C 18 , 5 mm Symmetry column (Waters, Watford, Herts, UK) using the mobile phase at a¯ow rate of 1 mL/min at ambient temperature. Peaks were detected using a Perkin Elmer LS5 spectro¯uorimeter (Perkin Elmer, Beacons®eld, Bucks, UK) at an excitation wavelength of 280 nm and emission wavelength of 345 nm. The internal standard peak eluted at 6´7 min and the 5-HIAA at 12´5 min. Lateeluting¯uorescent compounds were removed from the column by incorporating an acetonitrile wash for 1 min between sample injections. The method was calibrated using normal pooled plasma spiked with 5-HIAA concentrations of up to 1000 nmol/L. Samples with 5-HIAA greater than 1000 nmol/L were diluted in pooled plasma and re-analysed.Urine 5-HIAA was measured by HPLC using the method described by Skrinska and Hahn, 3 but substituting methanol in the mobile phase with acetonitrile. Heparinized blood samples were collected from 40 normal, fasting adult volunteers (14 men, 26 women) and 11 patients with carcinoid disease. Seven pairs of normal volunteers had both fasting and 2-h blood samples taken after ingestion of the following serotonin-containing food: plums, tomatoes, kiwi fruit, avocadoes, walnuts, pineapples and bananas.Plasma 5-HIA...

Background Micronutrient deficiencies may occur in patients with malignancy due to a variety of possible causes, including unbalanced dietary intake and adverse effects of treatment. In addition, many patients show signs of a chronic inflammatory response, which can affect circulating concentrations of certain vitamins and trace elements. Our aim was to examine the effect of the inflammatory response, as determined by plasma C-reactive protein (CRP) concentrations, on a range of micronutrients in patients with malignancy.