Our data in a large and modern day pHPT series, with a preponderance of asymptomatic patients, confirm increased insulin resistance and pre-valence of IGT and undiagnosed diabetes.
Our study shows that VDD occurs in about one-third of patients with pHPT resident in a Southern European area, a lower figure than previously reported. Moreover, VDD is related to a more severe bone disease, and its prevalence is higher in patients with pHPT than in healthy matched subjects.
Insulinoma is characterized by spontaneous fasting hypoglycemia. Diagnosis relies on inappropriately increased insulin levels (>6 microU/ml), high insulin/glucose ratio (IGR >0.3), raised proinsulin values (>5 pMol/l). A 74-yr-old man was referred to us for episodes of symptomatic hypoglycemia without hyperinsulinemia and imaging [abdominal computed tomography (CT) and magnetic resonance scans] negative for neuroendocrine tumor (NET). During hospitalization severe hypoglycemic crises persisted requiring continuous glucose iv infusion. Insulin values (immunofluorimetric method) were not inappropriately increased, accordingly IGR was normal but C-peptide was in the upper-normal range. Proinsulin levels measured with specific radioimmunoassay were remarkably high. Octreoscan study was negative whereas endoscopic ultrasound disclosed a 10 mm lesion in the body of the pancreas, confirmed by rapid spiral CT scanning with dynamic images. Increased proinsulin levels allowed diagnosis of a secreting NET. After removal of the lesion, the patient experienced hyperglycemia. Histology confirmed a benign NET positively staining for insulin. In conclusion, proinsulin assay is of particular help when immunoreactive insulin, measured by specific new immunometric assays (immunoenzymometric and immunofluorimetric assays), is normal. These methods have good precision and specificity (no cross reactivity with intact or Des 31,32 proinsulin), but rare insulinomas secreting most, or all, of their insulin-like activity as proinsulins would go undetected if insulin levels alone were measured.
Since 1989, 45 patients [pts; 26 females and 19 males, aged 19-79 yr (median, 58)] bearing incidentally discovered adrenal masses were studied. The aim of the study was to verify the prevalence of hormone activity in clinically silent adrenal masses. Endocrine work-up included determination of urinary catecholamines and their metabolites, measurement of PRA and aldosterone levels in clino- and orthostatic posture, and basal and dynamic [dexamethasone (dex) suppression and ovine CRH stimulation] evaluation of hypothalamic-pituitary-adrenal axis. The most frequent finding was the reduction of dehydroepiandrosterone sulfate (DHEA-S) levels below the third percentile of controls in 19 (42%) pts. DHEA-S levels were significantly lower in pts than in controls [68 (range, 5-1000) vs. 208 (34-326) micrograms/dL; 1.8 (0.1-27.1) vs. 5.6 (0.9-8.8) mumol/L; P < 0.001]. Three pts (7%) had high 24-h mean serum cortisol levels, and 6 (14%) had blunted day-night amplitude of cortisol rhythm. Defective dex suppressibility was found in 15% of pts vs. 8% of controls (P < 0.05). ACTH and cortisol responses to ovine CRH did not significantly differ between pts and controls, although blunted ACTH responses were found in 22% of the cases. The above-mentioned endocrine alterations could be accounted for by autonomous cortisol secretion by the adrenal nodule at a rate not sufficient to give clinical expression, but able to inhibit to some extent the hypothalamic-pituitary-adrenal axis. These results indicate that silent cortisol hypersecretion is frequently observed in pts with adrenal incidentaloma even if progression to overt Cushing's syndrome seems unlikely. Indeed, the size of the mass and the hormone pattern remained substantially unchanged in 9 pts followed up for 12 months. From merely a cost/benefit ratio, the evaluation of DHEA-S levels and dex suppression has sufficient sensitivity to identify the occurrence of silent hypercortisolism.
In PHPT a slight decrease in renal function is associated with more severe BMD decrease, independent of age, body mass index, and PTH levels. This association is also present in asymptomatic PHPT and strengthens the National Institutes of Health recommendations for surgery in patients with mild PHPT.
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