Laboratory approaches for the diagnosis and assessment of hypercalcemia.

Calcium, the fifth most common element in the body, plays major physiological functions. Measurement of blood calcium is one of the most commonly ordered laboratory tests in assessments of calcium homeostasis and disease diagnosis. Hypercalcemia is an increased level of calcium in the blood. This disorder is most commonly caused by primary hyperparathyroidism and malignancy. However, other less common causes of elevated calcium levels need to be considered when making a differential diagnosis. This review is intended to provide readers with a better understanding of calcium homeostasis and the causes and pathophysiology of hypercalcemia. Most importantly, this review describes useful approaches for laboratory scientists and clinicians to appropriately diagnose and assess hypercalcemia.

Urinary and plasma catecholamines and urinary catecholamine metabolites in pheochromocytoma: diagnostic value in 19 cases.

We review our data on the measurement of catecholamines and their metabolites in 19 patients with pheochromocytoma. All the assays were specific high-performance liquid chromatographic procedures with electrochemical detection. The assay of fractionated metanephrines was 100% sensitive. Normal values for both urinary norepinephrine and epinephrine were found in two asymptomatic patients with pheochromocytoma. Normal values for 3-methoxy-4-hydroxymandelic acid (VMA) were found in two patients with pure epinephrine-secreting tumors and in one patient with multiple endocrine neoplasia type II. Plasma catecholamines were usually less increased than their urinary counterparts. We recommend the specific measurement of norepinephrine and epinephrine as the initial test for patients with suggestive symptoms, and specific measurement of normetanephrine and metanephrine for patients in whom an adrenal mass is incidentally found. We argue against the use of total metanephrines, total catecholamines, and VMA because of their lack of diagnostic sensitivity.

Phaeochromocytoma in multiple endocrine neoplasia type 2 A: survey of 100 cases.

OBJECTIVE: We report clinical, biochemical, morphological and histological data of phaeochromocytoma in 40 French families and in apparently sporadic cases of multiple endocrine neoplasia (MEN) type 2 A (medullary thyroid carcinoma, phaeochromocytoma, with or without hyperparathyroidism). DESIGN: This retrospective study was obtained from cases registered by the 'Groupe d'Etudes des Tumeurs à Calcitonine' from 1968 to 1990. We analysed the cases having sufficiently precise data on phaeochromocytoma with Pigas Software. PATIENTS: Characteristics of phaeochromocytoma in 100 patients with MEN 2 A were reviewed. Phaeochromocytoma was bilateral in 51%. The disease was inherited in 94 patients from 40 families (40 probands, 54 relatives), and was apparently sporadic in six. RESULTS: In this series, diagnostic circumstances were highly suggestive of phaeochromocytoma in 39.8% of the cases, whereas in 43.2%, diagnosis was made through systematic investigations of patients, either before (27.3%) or after (13.6%) thyroidectomy, or after discovery of hyperparathyroidism (2.3%). Fifteen per cent of patients were detected by family screening. Sudden death occurred in 8.9%, malignant phaeochromocytoma in 3%, and ectopic tissue in 4% of the cases. Urinary metanephrines appeared to be the most sensitive screening test. The extent of clinical symptoms was not associated with a particular hormonal pattern. Bilateral adrenalectomy was performed in 60% (in one step in 50%, in two steps in 10%). In these patients, bilateral histological lesions were observed in 92.5%. Simultaneous diagnosis for adrenal and thyroid disease was made in 73.4%, but phaeochromocytoma may be diagnosed before (9.6%) or after (17%) medullary thyroid carcinoma, with an interval greater than 2 years in 25 cases. CONCLUSION: Owing to variable clinical symptoms of phaeochromocytoma in these 100 cases of MEN 2 A, systemic biological adrenal assay is required. The search for phaeochromocytoma in medullary thyroid carcinoma (and vice versa) has to be systematically performed, even in apparently sporadic cases. Screening for phaeochromocytoma must be repeated for years, owing to the frequency of bilateral adrenal disease.

[Use of octreotide in the treatment of digestive endocrine tumors. A French multicenter study]. / Utilisation de l'octréotide dans les tumeurs endocrines digestives. Etude française multicentrique.

Morbidity and mortality in endocrine gastro-enteropancreatic (GEP) tumours are mainly related to the clinical consequences of tumoral peptide hypersecretion. Surgical resection at an early stage is the only curative treatment. However, most tumours are detected only when the hypersecretory state reflects the presence of metastases; surgery and chemotherapy then give only palliative results counterbalanced by serious side-effects. Somatostatin inhibits most endocrine secretions of the GEP tract and thus can alleviate invalidating symptoms. Its use is limited by its short half-life (2 min), the necessity of i.v. infusion and the possibility of a rebound phenomenon. Octreotide, a synthetic somatostatin analogue with a long duration of action, is administered subcutaneously and allows ambulatory treatment. In our series of 78 patients we observed about 80 percent of excellent or good clinical results, enabling the patients to resume normal life. Only minor and transient side-effects were noted. The overall tolerance of the drug was considered excellent or good. Prolonged administration of octreotide is a safe and effective symptomatic treatment in patients without any restriction of anti-tumoral procedures. Furthermore, it prevents the severe carcinoid crises that occur during surgery or embolization in patients with carcinoid syndromes.

Treatment of gastrointestinal endocrine tumours with interferon-alpha and octreotide.

This paper reports on the results of two controlled therapeutic trials on patients with endocrine tumours of the gastrointestinal tract. Seventeen patients were treated up to 18 months with recombinant interferon-alpha 2c (2 x 10(6) IU/m2 s.c. daily) and 16 patients are treated in an ongoing study with octreotide (3 x 200 micrograms daily). Objective response (greater than 50% reduction of hormone secretion) was observed in one of 15 evaluable patients on IFN-alpha and in 12 of 16 patients on octreotide. Reduction of tumour size was not observed in these two trials. However, the majority of patients had stable tumour size during IFN-alpha and octreotide treatment despite progressive disease before. Subjective improvement due to reduction of symptoms such as flushing, diarrhea, and dermatitis was significantly more frequent after octreotide than after IFN-alpha. Of five endocrine tumour patients with progressive disease on IFN-alpha, three responded to subsequent treatment with octreotide while one had stable disease and one progressed. Two cases are reported from the authors' series of patients treated with octreotide before start of these trials. Complete remission of the tumour by low-dose (2 x 100 micrograms daily) octreotide was observed in one carcinoid patient. This remission has now lasted for four years. In one patient with liver metastasis of a VIPoma, who had become resistant to streptozotocin, his watery diarrhoea is now completely controlled with 100 micrograms octreotide s.c. every second day.

Urinary metanephrine radioimmunoassay: comparison with the colorimetric assay.

A radioimmunoassay involving an 125I ligand has been developed and applied to the measurement of urinary metanephrine. To validate the clinical usefulness of this assay, we compared measurement of metanephrine by radioimmunoassay and of total urinary metanephrines by the Pisano colorimetric method. The radioimmunoassay is specific for metanephrine, whereas the colorimetric method measures both metanephrine and normetanephrine. We used both methods to determine urinary metanephrine or total metanephrines in subjects with essential hypertension, pheochromocytoma, the syndrome of multiple endocrine adenomatosis type 2, and normotensive volunteers. The mean and upper limit of normal (3 SD) for metanephrine by radioimmunoassay in our normotensive volunteers was 94.2 microgram/24 h and 229 microgram/24 h, respectively, which compares well with reported values of 87.6 microgram/24 h and 319 microgram/24 h by non-radioimmunoassay methods. Both radioimmunoassay and colorimetry accurately identified five patients with known pheochromocytoma. Good correlation (r = 0.993) was demonstrated between the two assays in a comparison of patients with essential hypertension and pheochromocytoma. We conclude that the radioimmunoassay is at least equivalent to the colorimetric methods in distinguishing pathological and normal catecholamine secretion, and is faster, more precise, and 1000-fold more sensitive.