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SUMMARY Dilated cardiomyopathy (DCM) is characterized by systolic dysfunction and is usually idiopathic. A rare cause of reversible DCM is hypocalcemia. Calcium plays a key role in myocardial contraction. Hypocalcemia can lead to a decrease in contraction, left ventricular systolic dysfunction, and heart failure with reduced ejection fraction (EF). Hypocalcemia-related reversible DCM reports are rare. Herein, we present two cases with heart failure caused by hypocalcemia developed due to hypoparathyroidism. The first case presented with severe heart failure and an extremely low serum calcium level (4.4 mg/dL) due to idiopathic hypoparathyroidism. The second case, which was also admitted with heart failure due to hypocalcemia, had iatrogenic hypoparathyroidism due to a subtotal thyroidectomy. In both cases, patients had reduced left ventricular systolic functions (EF was 33% and 42%, respectively). After calcium replacement and heart failure treatment, calcium levels were normalized. A significant and rapid improvement in heart failure was achieved in both cases (EF 60% and 50%, respectively). Serum calcium levels should always be measured in patients with heart failure, and the etiology of hypocalcemia should be sought. In addition to the standard pharmacotherapy of heart failure with reduced EF, calcium supplementation is essential for treating these patients.

Introduction: Insulinoma is a rare disease, however the most common cause of hypoglycemia due to excess insulin secretion. Diagnosis and localization can be challenging. This study evaluated the clinical features, diagnostic workup, management, and outcomes of patients with insulinoma. Methods: The records of 13 patients with insulinoma who were followed up at İstanbul University, İstanbul Faculty of Medicine were retrospectively reviewed. Results: The mean age of the 13 patients (female/male: 11/2) was 43.9±12.5 years at diagnosis. The mean tumor diameter was 14.3±6.7 mm and localized at the head in 30.8%, at the tail and/or body in 61.6%, and at both the head and body in 7.6% of patients. The tumor was correctly localized by magnetic resonance imaging in 10/13 patients, 68Ga DOTATATE positron emission tomography/computed tomography in 4/8, endoscopic ultrasound in 3/7, and selective arterial calcium stimulation in 4/4 patients. Eleven patients were operated. Distal pancreatectomy was performed in 4 patients, distal pancreatectomy plus splenectomy in 3, and enucleation in 4 of the patients. The median follow-up duration was 4 years. In 8 patients, cure was achieved with surgery alone. Somatostatin receptor analog (SSRA) treatment was initiated in 2 cases and one of whom developed lymph node metastasis 2.5 years after surgery under SSRA treatment and she was reoperated. These patients had stable disease at the last visit. Conclusion: Insulinomas are usually small tumors, but they can cause severe symptoms. A multidisciplinary approach is required for diagnosis and treatment. In some patients, different imaging modalities may be necessary for tumor localization.

Objective:A 35-year-old Turkish male patient was referred to us with a year-long history of joint paint and congenital hearing loss. Family history revealed more family members with hearing loss without paraneoplastic syndrome. These findings led us to investigate the genetic alterations associated with familial hypophosphatemia, which revealed an ENPP1 mutation.Methods:Serum samples were obtained after 12-hour fasting. The mutation analysis was performed using previously described primers. Total RNA was isolated from blood samples using Qiagen Total RNA extraction mini kit. cDNA samples were amplified using polymerase chain reaction (PCR), and these PCR products were purified using commercial kits. Following amplification and purification, the PCR products were sequenced.Results:The patient was found to have hypophosphatemia, a high level of PTH, and elevated plasma alkaline phosphatase. Sequencing results revealed an ENPP1 p.D85H mutation.Conclusion:We present the identification of an inactivating mutation in the ectonucleotide pyrophosphatase/phosphodiesterase-1. The substituted amino acid residue is highly conserved in ENPP1. At present, we have no further explanation, but our results suggest that ENPP1 p.D85H mutation may be associated with hypophosphatemic rickets accompanied by hearing loss.

OBJECTIVE: Fibroblast growth factor 23 (FGF23), a phosphatonin, inhibits renal phosphate reabsorption and suppresses 1-α hydroxylase activity. Calcitriol stimulates FGF23 synthesis in bone. We aimed to determine the effect of vitamin D replacement therapy on serum FGF23 concentrations in vitamin D-deficient women and to compare the FGF23 concentrations of vitamin D-deficient patients with healthy subjects and patients with genetically determined hypophosphatemic rachitis. DESIGN AND METHODS: The study group was composed of vitamin D-deficient females (n=18, mean age 29.1±9.9 years), vitamin D-sufficient healthy females (control group; n=19, mean age 28.5±5.2 years), and patients with genetically determined hypophosphatemic rachitis (n=13, mean age 26.5±15.1 years). The groups were compared for serum FGF23, 1,25-dihydroxyvitamin D3 (1,25(OH)2D), calcium, phosphate, bone turnover markers, intact parathyroid hormone (PTH), and urinary excretion of calcium and phosphate. The vitamin D-deficient group was re-evaluated after a standard treatment regimen. RESULTS: Serum FGF23 concentrations were significantly lower in vitamin D-deficient patients than in vitamin D-sufficient women and hypophosphatemic rachitis group. Serum FGF23 and phosphate concentrations further decreased significantly during replacement of vitamin D (P<0.05). A significant negative correlation was evident between FGF23 and PTH before vitamin D replacement in the patients (r=–0.469, P<0.05). CONCLUSION: Decreased FGF23 concentrations, which further decline during vitamin D replacement therapy, may have favorable action on bone mineralization by counterregulatory effect on phosphate homeostasis. Lower 1,25(OH)2D concentrations at baseline and hypophosphatemia during treatment may have dominating effects on FGF23 concentrations in vitamin D deficiency, leading to decreased FGF23 concentrations at baseline and during replacement therapy. [ABSTRACT FROM AUTHOR]