Evaluation of 5-hydroxyindoloacetic acid excretion in urine in patients with small intestine neuroendocrine neoplasm and carcinoid syndrome treated with somatostatin analogues.

BACKGROUND: The assessment of hormonal function of neuroendocrine neoplasm (NEN) is an important stage in the diagnosis and monitoring of these diseases treatment. Objective of this study was to analyze the results of urinary excretion of 5-hydroxyindoloacetic acid (5-HIAA) in patients with carcinoid syndrome treated with somatostatin analogues, depending on the histologic maturity, degree of liver involvement and stage of the disease. METHODS: The final group comprised of 41 patients. All patients were subject to surgical removal of the primary site. Presence of hepatic metastases was determined in all patients. All patients were treated with somatostatin analogues. The 5-HIAA urine excretion was determined using the ELISA immunoenzymatic method. RESULTS: The mean excretion of 5-HIAA in patients with histological maturity grade G1 was 45.64 mg/24h, while in the group G2 the mean excretion was 108.41 mg/24h and was higher than in the group G1 (p=0.003). In the analysis of 5-HIAA value depending on the degree of liver involvement, the mean value of 5-HIAA excretion in patients with 10% liver involvement was 38.99 mg/24h, whereas in patients with 25% liver involvement this value was considerably higher and amounted 131.00 mg/24h (p< 0.001). In patients with disease progression the mean excretion was 117.37 mg/24h compared to the group of patients with stabilization of the disease, where the mean value was lower and amounted to 39.39 mg/24h (p<0.001). CONCLUSION: Assessment of 5-HIAA excretion in patients with carcinoid syndrome is of considerable significance in the diagnostics and monitoring of the treatment.

Telotristat ethyl in carcinoid syndrome: safety and efficacy in the TELECAST phase 3 trial.

Telotristat ethyl, a tryptophan hydroxylase inhibitor, was efficacious and well tolerated in the phase 3 TELESTAR study in patients with carcinoid syndrome (CS) experiencing ≥4 bowel movements per day (BMs/day) while on somatostatin analogs (SSAs). TELECAST, a phase 3 companion study, assessed the safety and efficacy of telotristat ethyl in patients with CS (diarrhea, flushing, abdominal pain, nausea or elevated urinary 5-hydroxyindoleacetic acid (u5-HIAA)) with <4 BMs/day on SSAs (or ≥1 symptom or ≥4 BMs/day if not on SSAs) during a 12-week double-blind treatment period followed by a 36-week open-label extension (OLE). The primary safety and efficacy endpoints were incidence of treatment-emergent adverse events (TEAEs) and percent change from baseline in 24-h u5-HIAA at week 12. Patients (N = 76) were randomly assigned (1:1:1) to receive placebo or telotristat ethyl 250 mg or 500 mg 3 times per day (tid); 67 continued receiving telotristat ethyl 500 mg tid during the OLE. Through week 12, TEAEs were generally mild to moderate in severity; 5 (placebo), 1 (telotristat ethyl 250 mg) and 3 (telotristat ethyl 500 mg) patients experienced serious events, and the rate of TEAEs in the OLE was comparable. At week 12, significant reductions in u5-HIAA from baseline were observed, with Hodges-Lehmann estimators of median treatment differences from placebo of -54.0% (95% confidence limits, -85.0%, -25.1%, P < 0.001) and -89.7% (95% confidence limits, -113.1%, -63.9%, P < 0.001) for telotristat ethyl 250 mg and 500 mg. These results support the safety and efficacy of telotristat ethyl when added to SSAs in patients with CS diarrhea (ClinicalTrials.gov identifier: Nbib2063659).

Telotristat Ethyl, a Tryptophan Hydroxylase Inhibitor for the Treatment of Carcinoid Syndrome.

Purpose Preliminary studies suggested that telotristat ethyl, a tryptophan hydroxylase inhibitor, reduces bowel movement (BM) frequency in patients with carcinoid syndrome. This placebo-controlled phase III study evaluated telotristat ethyl in this setting. Patients and Methods Patients (N = 135) experiencing four or more BMs per day despite stable-dose somatostatin analog therapy received (1:1:1) placebo, telotristat ethyl 250 mg, or telotristat ethyl 500 mg three times per day orally during a 12-week double-blind treatment period. The primary end point was change from baseline in BM frequency. In an open-label extension, 115 patients subsequently received telotristat ethyl 500 mg. Results Estimated differences in BM frequency per day versus placebo averaged over 12 weeks were -0.81 for telotristat ethyl 250 mg ( P < .001) and ‒0.69 for telotristat ethyl 500 mg ( P < .001). At week 12, mean BM frequency reductions per day for placebo, telotristat ethyl 250 mg, and telotristat ethyl 500 mg were -0.9, -1.7, and -2.1, respectively. Responses, predefined as a BM frequency reduction ≥ 30% from baseline for ≥ 50% of the double-blind treatment period, were observed in 20%, 44%, and 42% of patients given placebo, telotristat ethyl 250 mg, and telotristat ethyl 500 mg, respectively. Both telotristat ethyl dosages significantly reduced mean urinary 5-hydroxyindole acetic acid versus placebo at week 12 ( P < .001). Mild nausea and asymptomatic increases in gamma-glutamyl transferase were observed in some patients receiving telotristat ethyl. Follow-up of patients during the open-label extension revealed no new safety signals and suggested sustained BM responses to treatment. Conclusion Among patients with carcinoid syndrome not adequately controlled by somatostatin analogs, treatment with telotristat ethyl was generally safe and well tolerated and resulted in significant reductions in BM frequency and urinary 5-hydroxyindole acetic acid.

Telotristat etiprate for carcinoid syndrome: a single-arm, multicenter trial.

CONTEXT: Carcinoid syndrome (CS) is associated with elevated serotonin, diarrhea, flushing, and increased risk of valvular heart disease. Many patients respond to somatostatin analogs initially, but response diminishes in most patients. Additional options are needed. OBJECTIVE: To assess whether telotristat etiprate (TE) can reduce gastrointestinal symptoms in CS and reduce urinary 5-hydroxyindoleacetic acid (u5-HIAA; a biomarker of serotonin). DESIGN: A prospective, exploratory, dose-escalating 12-week, open-label, multicenter study of TE with efficacy and safety analyses. SETTING: A multicenter study. PATIENTS: Eligible patients had metastatic, well-differentiated, neuroendocrine tumors and CS with ≥ four bowel movements (BMs) per day. Somatostatin analog use was allowed. INTERVENTIONS: TE, a novel oral inhibitor of peripheral serotonin synthesis. MAIN OUTCOME MEASURES: Primary: safety. Secondary: daily BMs, stool form, and u5-HIAA. RESULTS: Fifteen patients were enrolled, and 14 completed the treatment period. All patients experienced reductions in BMs per day (mean decrease, 43.5%). A 74.2% mean reduction in u5-HIAA, the main metabolite of serotonin, was observed, with generally greater reductions in patients with greater reductions in BMs per day. Nine patients (75%) reported "adequate relief" of gastrointestinal symptoms at 12 weeks, compared with two (17%) at baseline. Stool form and flushing also improved. Adverse events were mostly gastrointestinal (n = 10; 67%), consistent with underlying illness; three adverse events were serious (abdominal pain, diarrhea, and gastroenteritis) but were judged unrelated. CONCLUSION: TE was generally safe and well tolerated. Patients experienced substantial improvement in CS and reductions in u5-HIAA, consistent with the mechanism of action of TE. These results support further evaluation in phase 3 studies.

Telotristat etiprate, a novel serotonin synthesis inhibitor, in patients with carcinoid syndrome and diarrhea not adequately controlled by octreotide.

Serotonin produced by neuroendocrine tumors is believed to be a principal cause of the diarrhea in carcinoid syndrome. We assessed the safety and efficacy of telotristat etiprate, an oral serotonin synthesis inhibitor, in patients with diarrhea associated with carcinoid syndrome. In this prospective, randomized study, patients with evidence of carcinoid tumor and ≥4 bowel movements (BMs)/day despite stable-dose octreotide LAR depot therapy were enrolled in sequential, escalating, cohorts of four patients per cohort. In each cohort, one patient was randomly assigned to placebo and three patients to telotristat etiprate, at 150, 250, 350, or 500 mg three times a day (tid). In a subsequent cohort, one patient was assigned to placebo and six patients to telotristat etiprate 500 mg tid. Patients were assessed for safety, BM frequency (daily diary), 24 h urinary 5-hydroxyindoleacetic acid (u5-HIAA), and adequate relief of carcinoid gastrointestinal symptoms (using a weekly questionnaire). Twenty-three patients were treated: 18 received telotristat etiprate and five received placebo. Adverse events were generally mild. Among evaluable telotristat etiprate-treated patients, 5/18 (28%) experienced a ≥30% reduction in BM frequency for ≥2 weeks, 9/16 (56%) experienced biochemical response (≥50% reduction or normalization in 24-h u5-HIAA) at week 2 or 4, and 10/18 (56%) reported adequate relief during at least 1 of the first 4 weeks of treatment. Similar activity was not observed in placebo-treated patients. Telotristat etiprate was well tolerated. Our observations suggest that telotristat etiprate has activity in controlling diarrhea associated with carcinoid syndrome. Further studies confirming these findings are warranted.

Circulating serotonin and bone density, structure, and turnover in carcinoid syndrome.

CONTEXT: Gut-derived serotonin has been proposed as a regulator of bone formation, and inhibition of gut serotonin synthesis increases bone formation in rodents. Carcinoid neuroendocrine tumors can produce very high levels of circulating serotonin and so offer a model of serotonin excess in humans. OBJECTIVES: The objective of the study was to determine whether patients with carcinoid syndrome have lower bone formation markers, lower bone density, or poor bone structure compared with healthy controls. DESIGN: We conducted a cross-sectional study of 25 patients with carcinoid syndrome and 25 healthy controls, individually matched to carcinoid patients by gender, age, height, and body mass index. OUTCOME MEASURES: We measured circulating serotonin in blood and plasma and 5-hydroxyindoleacetic acid (5HIAA) in plasma and urine. We measured lumbar spine and hip bone mineral density by dual-energy x-ray absorptiometry, the distal radius and tibia with high-resolution peripheral quantitative computed tomography, and bone turnover with serum osteocalcin, amino-terminal propeptide of type I procollagen (PINP) and C-terminal telopeptide of type I collagen (CTX). RESULTS: All measures of serotonin and 5HIAA were higher in carcinoid patients than in controls. No measures of bone density or bone structure differed significantly between cases and controls. Osteocalcin was higher in the cases than controls (26.0 vs 21.1 ng/mL, P = .02). PINP and CTX did not differ between cases and controls. In patients with carcinoid syndrome, plasma 5HIAA was positively correlated with osteocalcin. In controls, whole-blood serotonin was positively correlated with osteocalcin, PINP, and CTX (R values = 0.40-0.47, all P < .05.). CONCLUSIONS: High circulating serotonin in carcinoid syndrome is not associated with clinically significant lower bone density, poorer bone structure, or lower bone formation markers.

'Sweet Dreams', 'Happy Days' and elevated 24-h urine 5-hydroxyindoleacetic acid excretion.

We report two patients with markedly elevated 24-h urine 5-hydroxyindoleacetic acid (5-HIAA) excretion due to over-the-counter (OTC) self-medication with 5-hydroxytryptophan (5-HTP). It is important to recognize that OTC medication may cause increased 'false-positive' 5-HIAA excretion to prevent undue patient anxiety and unnecessary further investigation for carcinoid disease. Discordance between chromogranin A and 24-h urine 5-HIAA results should alert to the possibility of false-positive or -negative laboratory results.

5-HIAA excretion is not associated with bone metabolism in carcinoid syndrome patients.

In patients with a carcinoid syndrome and neuroendocrine tumors of the digestive tract (carcinoids), elevated circulating serotonin (5-hydroxytryptamine, 5-HT) levels can be demonstrated. It can be hypothesized that bone metabolism will be affected in these patients, since serotonin receptors are expressed on bone cells and serotonin effects on bone have been demonstrated. However, to date, no data are available on bone metabolism parameters in patients with neuroendocrine tumors of the digestive tract (carcinoids). In the current retrospective study we have measured serum bone formation markers P1CP (pro-collagen type I C-terminal), and osteocalcin, and the bone resorption marker NTx (collagen breakdown product N-terminal), in a group of 61 carcinoid patients with increased circulating serotonin levels as demonstrated by increased excretion of the serotonin breakdown product, 5-hydroxy indole acetic acid (5-HIAA), in the urine (>50 µmol/24 h, so-called "hyper-secretors") and a control group of 23 carcinoid patients, without increased 5-HIAA excretion (so-called non-secretors). The 24-h urinary excretion of 5-HIAA reflects the 24-h production of serotonin. Measurements of markers of bone metabolism were performed in serum samples obtained before the start of medical treatment. The hypersecretor group had on average a 10-fold higher urinary 5-HIAA excretion than the control (non-secretor) group. No significant differences in bone metabolism parameters could be demonstrated between hyper-secretors and controls (non-secretors). Correlation and regression analyses could not demonstrate significant age- and sex-adjusted correlations between urinary 5-HIAA excretion and any of the markers for bone turnover. A limitation is that the exposure time to elevated levels of serotonin is unknown, which might have been too short to induce effects on bone metabolism. Treatment of human pre-osteoblasts SV-HFO with serotonin didn't change alkaline phosphatase activity throughout differentiation as well as mineralization. In conclusion, the current study in a unique group of untreated carcinoid patients could not demonstrate a major role for circulating serotonin in the control of bone metabolism.

Case report--carcinoid syndrome: two case reports from reserve unit.

Carcinoid tumours are uncommon and carcinoid syndrome is likely to be encountered only occasionally during a clinical career outside the Neuro-endocrine and related specialties. Two cases of carcinoid syndrome are described in Royal Naval Reserve (RNR) personnel presenting simultaneously in the same unit. Both had long histories and, despite early contact with medical staff, had for some time been dismissed as having trivial complaints. Both have responded well to treatment, though neither has been able to have curative surgery. The current methods of diagnosis which allow much earlier identification and localisation of these tumours are discussed. We also review the management options now available which will control disease and allow the patient to pursue their chosen career, be it military or civil.

Biochemical assessment of niacin deficiency among carcinoid cancer patients.

OBJECTIVE: Carcinoid cancer patients often have elevated levels of serotonin or its precursor 5-hydroxytryptophan. Normally, serotonin synthesis accounts for a small fraction of tryptophan catabolism, which should be directed along a pathway that allows partial conversion to niacin; hence, increased diversion of tryptophan toward serotonin could cause variable degrees of niacin deficiency in carcinoid patients. Therefore, the prevalence of niacin deficiency among carcinoid patients was investigated by clinical assessment of pellagra and biochemical assessment of whole blood niacin number, a ratio derived from two biologically active forms of niacin (NAD/NADP x 100). METHODS: Clinical and biochemical niacin status were assessed in a cohort of newly diagnosed carcinoid patients with carcinoid syndrome (CCS, n = 36), carcinoid patients without carcinoid syndrome (CWCS, n = 32) and noncarcinoid controls (n = 24) recruited at two primary care clinics. Other aspects of serotonin metabolism were measured by analyses of plasma serotonin and tryptophan and urinary excretion of 5-hydroxyindoleacetic acid. RESULTS: Biochemical niacin deficiency (niacin number < 130) was significantly more common in CCS patients (10 out of 36) compared to controls (p < 0.05, Fisher's exact test), while CWCS patients displayed an incidence that was not significantly elevated (4 out of 32). Only one CCS patient, who was also identified biochemically as niacin deficient, was clinically diagnosed with pellagra. CONCLUSION: Biochemical niacin deficiency is more prevalent among newly diagnosed CCS patients than in controls. Manifestation of pellagra is a less sensitive indicator, and dependence on this endpoint could lead to a lack of appropriate nutritional support for this group of patients.

Angioedema as a single manifestation of carcinoid syndrome in a bronchial carcinoid tumor.

BACKGROUND: The association of bronchial carcinoid tumours with carcinoid syndrome is extremely rare especially in the absence of metastasic disease, and the angioedema is not a typical sign of this syndrome. METHODS AND RESULTS: We report the case of a 39 year-old woman referred to our allergy department with recurrent episodes of angioedema. The aetiological study of angioedema did not show evidence of hypersensitivity to common inhalants, food allergens and latex. C1-inhibitor, C3, C4, C1q, proteinogram and immunoglobulins (IgA, IgG, IgM) all were normal. TSH determination gave normal results, too. Faecal analyses for parasites were negative. The haemogram showed moderate leucocytosis and hypocromic mycrocitic anaemia. The thoracic radiography showed a mediastinal node image in the right paratracheal region. Histology analyses of the samples were diagnostic of a typical carcinoid tumor. Levels of 5-hydroxyindolacetic acid (5-HIIA) were slightly increased. A superior lobectomy was performed and no new episodes of angioedema appeared after surgical intervention. CONCLUSIONS: We report the first case of typical bronchial carcionid tumour, without metastasic disease, with angioedema as a single manifestation of carcinoid syndrome. In our knowledge, only one case of Quincke's edema as part of typical carcinoid syndrome has been reported, in a case of primary midgut carcinoid tumor with metastasic disease to liver. It is very important to include complementary tests, as thoracic radiography, in the routine study of angioedema to reject malignant diseases.

Prediction of prognosis by echocardiography in patients with midgut carcinoid syndrome.

BACKGROUND: The association between malignant midgut carcinoid tumours and right-sided cardiac lesions is well known, but the pathogenetic link between tumour secretion and valvular disease is still obscure. The purpose of this investigation was to describe the morphological and functional changes of valvular heart disease in a large patient series and to correlate these findings with hormonal secretion and prognosis. METHODS: Of 64 consecutive patients with the midgut carcinoid syndrome followed between 1985 and 1998, valvular heart disease was evaluated in 52 patients by two-dimensional echocardiography, Doppler estimation of valvular regurgitation and flow profiles. A majority was also evaluated with exercise electrocardiography and spirometry. RESULTS: Structural and functional abnormalities of the tricuspid valve were found in 65 per cent of patients, while only 19 per cent had pulmonary valve regurgitation. Long-term survival was related to excessive urinary excretion of 5-hydroxyindole acetic acid of over 500 micromol in 24 h, but the main predictor of prognosis was the presence of severe structural and functional abnormalities of the tricuspid valve. Although advanced tricuspid abnormalities were prevalent in this series, only one patient died from right ventricular heart failure. CONCLUSION: Tricuspid valvular disease is a common manifestation of the midgut carcinoid syndrome and advanced changes are associated with poor long-term survival. Active surgical and medical therapy of the tumour disease reduced the hormonal secretion and, combined with cardiological surveillance, made right ventricular heart failure a rare cause of death in these patients.

Octreotide acetate long-acting formulation versus open-label subcutaneous octreotide acetate in malignant carcinoid syndrome.

PURPOSE: Subcutaneous (SC) octreotide acetate effectively relieves the diarrhea and flushing associated with carcinoid syndrome but requires long-term multiple injections daily. A microencapsulated long-acting formulation (LAR) of octreotide acetate has been developed for once-monthly intramuscular dosing. PATIENTS AND METHODS: A randomized trial compared double-blinded octreotide LAR at 10, 20, and 30 mg every 4 weeks with open-label SC octreotide every 8 hours for the treatment of carcinoid syndrome. Seventy-nine patients controlled with treatment of SC octreotide 0.3 to 0.9 mg/d whose symptoms returned during a washout period and who returned for at least the week 20 evaluation constituted the efficacy-assessable population. RESULTS: Complete or partial treatment success was comparable in each of the four arms of the study (SC, 58.3%; 10 mg, 66.7%; 20 mg, 71.4%; 30 mg, 61.9%; P> or =.72 for all pairwise comparisons). Control of stool frequency was similar in all treatment groups. Flushing episodes were best controlled in the 20-mg LAR and SC groups; the 10-mg LAR treatment was least effective in the control of flushing. Treatment was well tolerated by patients in all four groups. CONCLUSION: Once octreotide steady-state concentrations are achieved, octreotide LAR controls the symptoms of carcinoid syndrome at least as well as SC octreotide. A starting dose of 20 mg of octreotide LAR is recommended. Supplemental SC octreotide is needed for approximately 2 weeks after initiation of octreotide LAR treatment. Occasional rescue SC injections may be required for possibly 2 to 3 months until steady-state octreotide levels from the LAR formulation are achieved.

The incidence of elevations in urine 5-hydroxyindoleacetic acid.

A 24-hour urine collection for 5-hydroxyindoleacetic acid (HIAA) is commonly performed to evaluate patients with suspected carcinoid syndrome. However, carcinoids are rare, and elevated results are common even when using an analytically specific method. To characterize this problem, the incidence of elevated results was examined in a population of 947 patient specimens received in a clinical reference laboratory setting. Using a reference limit of 15 mg/d identified 7.9 percent of the results as elevated, with 3 percent > 100 mg/d, and about 1 percent > 350 mg/d. Males showed 14 percent > 15 mg/d compared to 5.2 percent for females. Characterization of incomplete and excess 24-hr urine collections is facilitated by use of a creatinine ratio, with a reference limit of 14 mg/g creatinine equivalent to 15 mg/d. Given the frequency of elevated results, HIAA should be used to support the diagnoses of carcinoid only when consistent with other objective findings.

Pseudocarcinoid syndrome associated with hypogonadism and response to testosterone therapy.

OBJECTIVE: To characterize a disorder of episodes of flushing and increased levels of 5-hydroxyindoleacetic acid (5-HIAA) in men with secondary hypogonadism who respond to testosterone therapy. MATERIAL AND METHODS: We present detailed case reports of three male patients who had flushing, secondary hypogonadism, and increased urinary 5-HIAA levels and describe their clinical and laboratory features before and after treatment with testosterone. In addition, six male patients with hypogonadism (three with primary and three with secondary hypogonadism) without flushing were assessed. RESULTS: The three patients with flushing and secondary hypogonadism (serum total testosterone 5.45 +/- 0.63 nmol/L, free testosterone 89.3 +/- 7.0 pmol/L, follicle-stimulating hormone 3.85 +/- 0.58 IU/L, and luteinizing hormone 4.41 +/- 0.98 IU/L) had increased urinary 5-HIAA levels (98.5 +/- 12.2 micromol/24 h) but normal blood serotonin levels (9.66 +/- 1.58 micromol/L). During a pentagastrin-calcium stimulation test, serum calcitonin and blood serotonin values were normal in patients with secondary hypogonadism and flushing. Detailed investigation showed no evidence of a carcinoid tumor. Urinary 5-HIAA levels became normal (16.6 +/- 1.73 micromol/24 h) after treatment with testosterone. When testosterone therapy was discontinued in two patients, flushing and increased urinary 5-HIAA levels recurred. Furthermore, flushing and the elevated urinary 5-HIAA values resolved when testosterone treatment was reinitiated. The six patients with hypogonadism without flushing had normal urinary 5-HIAA levels (14.9 +/- 3.31 micromol/24 h). CONCLUSION: Male patients with flushing and increased urinary 5-HIAA levels should undergo assessment for hypogonadism after screening for carcinoid tumor. If hypogonadism is diagnosed, resolution of flushing and normalization of 5-HIAA may be achieved with testosterone treatment. We suggest that pseudocarcinoid syndrome associated with hypogonadism be the descriptive label used for this combination of clinical features.

Immunoassays for measurement of chromogranin A and pancreastatin-like immunoreactivity in humans: correspondence in patients with neuroendocrine neoplasia.

Chromogranin A (CgA) is a useful marker of neuroendocrine tumors in humans. Here we describe and compare two immunoassay methods for determination of CgA, a radioimmunoassay (RIA) and an enzyme linked immunoassay (ELISA). The detection limit of the ELISA was lower than that of the RIA method (2 ng/ml versus 10 ng/ml, respectively), though the CgA RIA method covered a wider range than the CgA ELISA (10-920 ng/ml versus 2-500 ng/ml, respectively). There was no cross-reactivity with synthetic human and porcine pancreastatin (PST) in the two assays. There was a significant positive correlation between levels of CgA in sera from patients with carcinoid disease, measured by the two methods (r = 0.9, p < 0.0001), and the values were in the same range. Similarly, serum CgA levels in normal controls were also in the same range when assayed by the two methods. A commercially available porcine PST RIA method was evaluated, especially with respect to the influence of Sep-Pak extraction of serum on the levels of pancreastatin-like immunoreactivity (PST-LI). Ten sera from carcinoid patients were treated with Sep-Pak extraction, and levels of PST-LI were determined in non-extracted and extracted sera. There was a significant positive correlation between the concentrations of PST-LI measured in extracted and non-extracted carcinoid sera (r = 0.9, p < 0.002), and the levels were in the same range. There was also a significant positive correlation between levels of CgA and PST-LI in 49 carcinoid sera (r = 0.8, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Additional tests of interest to the dermatologist.

The carcinoid syndrome and its clinical manifestations have been discussed. The standard laboratory test for making that diagnosis is urinary 5-HIAA levels but newer, more sensitive tests may also be available.

Serotonin, catecholamines, histamine, and their metabolites in urine, platelets, and tumor tissue of patients with carcinoid tumors.

We monitored long-term (median 11 months) concentrations of platelet serotonin and urinary serotonin, 5-hydroxyindoleacetic acid, and seven catecholamine metabolites in 44 patients with carcinoid tumors. Tumor serotonin and catecholamine contents (11 patients) and urinary histamine and N-methylhistamine (15 patients) were determined. Consistently increased concentrations of indoles, notably platelet serotonin, were observed in 96%, 43%, and 0% of patients with mid-, fore-, and hindgut carcinoids, respectively. Urinary dopamine metabolites, notably 3-methoxytyramine, were consistently increased in 38%, 20%, and 7% of patients with mid-, hind-, and foregut carcinoids, respectively. For urinary norepinephrine/epinephrine metabolites, notably normetanephrine and metanephrine, these data were 33%, 20%, and 14%, respectively. Midgut carcinoid tumors had the highest serotonin contents, whereas concentrations of catecholamines were independent of primary localization. There was no consistent relation between biogenic amine contents in tumors and urinary excretion of the amine metabolites. Occurrence of carcinoid syndrome was related to increased serotonin production rate. Increased histamine production is not an important feature in patients with lung carcinoids or liver-metastasized ileum carcinoids.

An improvement of the endocrine diagnosis by high-performance liquid chromatography.

The assessment of catecholamines (NE, E), essential metabolites (VMA, HVA) and serotonergic metabolite 5HIIA in urine by HPLC with UV detection is of interest for clinical diagnosis concerning HTA, pheochromocytoma, neuroblastoma, carcinoid syndrome, hypotension, etc. In the same urine sample one can detect (following preliminary steps) by HPLC the above--mentioned biochemical parameters with good reproducibility and sensitivity.

Positron emission tomography (PET) in neuroendocrine gastrointestinal tumors.

Positron emission tomography (PET) makes it possible to study effects of medical treatment in vivo. Carcinoid tumors with liver metastases, especially those of midgut origin, produce serotonin via the precursors tryptophan and 5-hydroxytryptophan (5-HTP) and this overproduction contributes to the clinical symptoms of the carcinoid syndrome. Seven patients with histopathologically verified neuroendocrine tumors and liver metastases, five of whom with ileal carcinoids, one a lung carcinoid and one an endocrine pancreatic tumor, were included in the study. All patients had elevation of urinary 5-HIAA with the exception of one patient with a solitary liver metastasis of midgut origin. After an intravenous injection of 11C-5-HTP, PET was performed and the uptake of radioactivity in tumor tissue, normal liver and plasma were compared. All patients with elevated urinary 5-HIAA and also the patient with a solitary liver metastasis and normal urinary 5-HIAA had high accumulation and signs of a high rate of binding of 5-HTP in the liver metastases. The uptake was relatively homogeneous in midgut carcinoid liver metastases but in large necrotic metastases the radioactivity was localized to the periphery. In three patients PET examination was repeated after 3 months of interferon treatment and in agreement with circulating tumor markers and ultrasonography the uptake of 5-HTP was unchanged. Another patient who received the somatostatin analog somatuline progressed on treatment and accordingly the uptake of 5-HTP also increased. The experience with PET in neuroendocrine gastrointestinal tumors is very limited. Our results so far indicate that 5-HTP can be used to visualize serotonin-producing neuroendocrine tumors and furthermore it might prove to be of value to monitor the effects of treatment, possibly also as an early predictive test of the outcome of treatment.