Diagnosis and management of hypocalcemia.

The aim of this clinical narrative review is to summarize and critically appraise the literature on the differential diagnosis of hypocalcemia and to provide its correct management. Calcium is essential for muscle contraction and neurotransmitter release, but clinical manifestations of hypocalcaemia (serum calcium level <8 mg/dl; 2.12 mmol/L) may involve almost any organ and system and may range from asymptomatic to life-threating conditions. Disorders causing hypocalcemia can be divided into parathyroid hormone (PTH) and non-PTH mediated. The most frequent cause of hypocalcemia is postsurgical hypoparathyroidism, while a more comprehensive search for other causes is needed for appropriate treatment in the non PTH-mediated forms. Intravenous calcium infusion is essential to raise calcium levels and resolve or minimize symptoms in the setting of acute hypocalcemia. Oral calcium and/or vitamin D supplementation is the most frequently used as treatment of chronic hypocalcemia. In hypoparathyroidism, providing the missing hormone with the use of the recombinant human (rh) PTH(1-84) has been recently approved both by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This new therapy has the advantage of being effective for correcting serum calcium levels and significantly reducing the daily requirements of calcium and active vitamin D supplements. However, due to the high cost, a strict selection of candidates to this therapy is necessary. More challenging is the long-term hypocalcemia treatment, due to its associated complications. The development of long-acting recombinant human PTH will probably modify the management of chronic hypoparathyroidism in the future.

Investigating subtle kidney injury in primary hyperparathyroidism by means of sensitive and specific biomarkers.

OBJECTIVE: Kidney involvement is a common complication in primary hyperparathyroidism (PHPT). No study so far has assessed the prevalence of kidney injury developing before the reduction in glomerular filtration rate (GFR) in PHPT. The study was aimed at establishing the potential role of biomarkers of kidney injury in detecting subtle renal damage in patients with PHPT. DESIGN: Cross-sectional study. PATIENTS: A total of 69 postmenopausal patients with PHPT and 41 healthy age- and sex-matched subjects were studied. Exclusion criteria were as follows: GFR < 30 mL/min, chronic inflammatory disease, nephrotic syndrome, infection, malignancy, heart failure, recent exposure to iodinated contrast media or nonsteroidal anti-inflammatory drugs. MEASUREMENTS: We measured a panel of sensitive biomarkers of kidney injury in PHPT vs controls. RESULTS: Mean FGF23 and Klotho were higher in PHPT (72 ± 48 and 811 ± 366 pg/mL, respectively) than controls (53 ± 23.5 and 668.6 ± 17; P < .02 and P < .05). Urine KIM-1/uCr was significantly higher in PHPT (1.4-6  ± 1.3-6 ) than controls (9.2-7  ± 7-7 ; P < .05); this was particularly evident in the CrCl 60-89 mL/min category (1.36  ± 97 vs 8.2-7  ± 3.6-7 ; P < .02). Mean values of urine NGAL/uCr were higher in PHPT with (n = 28) compared to those without kidney stones (n = 35; 1.8-5  ± 1.4-5 and 1-5  ± 8-6 ; P < .0001). We found significant positive associations between urine NGAL/uCr and Ca (R = .292, P < .02) and urine KIM1/uCr and PTH (R = .329, P < .01). CONCLUSIONS: We propose the utilization of these molecules, particularly urine KIM-1/uCr and urine NGAL/uCr ratios for the assessment of subtle kidney injury in patients with PHPT. These molecules are elevated in tubular necrosis and have potential role in the development of kidney damage in PHPT, according to the severity of the disease.

Oral calcidiol is a good form of vitamin D supplementation.

Vitamin D supplementation represents an important topic in the field of metabolic bone disease. Calcidiol, the 25-hydroxy-vitamin D [25(OH)D], is the form of vitamin D most recently introduced in clinical practice. Advantages of the use of calcidiol derive from the pharmacokinetic properties and are related to the possibility of use in patients with liver disease, obese patients, patients with intestinal malabsorption, secondary hyperparathyroidism associated with chronic kidney disease as well as to avoid any possible toxic effect when high doses are used. The ADDI-D study demonstrated the efficacy and safety of calcidiol at the daily dose of 20 or 40 µg and 125 µg/week. In particular, the daily dose of 40 µg can be suggested as an alternative in severely deficient patients, as it has demonstrated to ensure higher vitamin D levels, compared to the 20 µg/day and the weekly 125 µg dose. The last can be an option when issues with compliance to the supplementation are present.