Long-term Efficacy and Safety of Rifampin in the Treatment of a Patient Carrying a CYP24A1 Loss-of-Function Variant.

BACKGROUND: Pharmacological therapy may be useful in the treatment of moderate to severe hypercalcemia in patients with infantile hypercalcemia-1 (HCINF1) due to pathogenic variants in the cytochrome P450 24 subfamily A member 1 (CYP24A1). Rifampin is an antituberculosis drug that is a potent inducer of cytochrome P450 3 subfamily A member 4, which is involved in an alternative catabolic pathway of vitamin D. The efficacy of rifampin in improving hypercalcemia was previously reported, but many questions remain on the long-term efficacy and safety. The aim of the study is to test the long-term efficacy and safety of rifampin in a patient with HCINF1. METHODS: We report clinical, biochemical, and imaging features of a 23-year-old man affected by HCINF1 with moderate hypercalcemia (12.9 mg/dL), symptomatic nephrolithiasis, nephrocalcinosis, and impaired kidney function [estimated glomerular filtration rate (eGFR) 60 mL/min/1.73 m2] treated with rifampin for an overall period of 24 months. Kidney, liver, and adrenal function were evaluated at every follow-up visit. RESULTS: In 2 months, rifampin induced a normalization of serum calcium (9.6 mg/dL) associated with an improvement of kidney function (eGFR 92 mL/min/1.73 m2) stable during the treatment. After 15 months, rifampin was temporally withdrawn because of asthenia, unrelated to impairment of adrenal function. After 3 months, the timing of drug administration was shifted from the morning to the evening, obtaining the remission of asthenia. At the end of follow-up, the nephrolithiasis disappeared and the nephrocalcinosis was stable. CONCLUSIONS: Rifampin could represent an effective choice to induce a stable reduction of calcium levels in patients with HCINF1, with a good safety profile.

Late-onset postsurgical hypoparathyroidism following parathyroidectomy for recurrent primary hyperparathyroidism: a case report and literature review.

PURPOSE: Previously in 1987, a 21-year-old male was diagnosed with primary hyperparathyroidism (PHPT) when a right inferior parathyroid adenoma was removed. PHPT recurred after 3 and 6 years and on both occasions was cured by resection of parathyroid adenomas. At 52 years of age, the patient developed a late-onset hypoparathyroidism (HP), even though postsurgical HP typically occurs as a transient or permanent form soon after neck surgery. The purpose of this work was to report the follow-up of the patient and to review prior cases of late-onset postsurgical HP. METHODS: Prior cases of late-onset postsurgical HP were searched and reviewed focusing on clinical and biochemical features. RESULTS: The patient's asymptomatic hypocalcemia with total serum calcium at 8.2 mg/dL was initially documented in September 2018; PTH was inappropriately low at 15 ng/mL. In February 2020, a mild hypocalcemia was confirmed with low-normal PTH at 15 ng/mL. Autoimmune and familial causes of HP were ruled out including the presence of stimulating autoantibodies against calcium-sensing receptor. Instead, a progressive damage or atrophy of the parathyroid gland(s) ensuing years after surgery is believed to have led to the patient's hypocalcemia. All 19 previously reported cases of late-onset postsurgical HP occurred after thyroid surgery, with no examples of the condition being found following parathyroidectomy. CONCLUSIONS: The case highlights the rare occurrence of late-onset postsurgical HP in a patient who had had multiple parathyroidectomies for PHPT. Thus, monitoring serum calcium, phosphate, and PTH during follow-up of such patients is recommended.

Screening of endocrine organ-specific humoral autoimmunity in 47,XXY Klinefelter's syndrome reveals a significant increase in diabetes-specific immunoreactivity in comparison with healthy control men.

The aim of this study was to evaluate the frequency of humoral endocrine organ-specific autoimmunity in 47,XXY Klinefelter's syndrome (KS) by investigating the autoantibody profile specific to type 1 diabetes (T1DM), Addison's disease (AD), Hashimoto thyroiditis (HT), and autoimmune chronic atrophic gastritis (AG). Sixty-one adult Caucasian 47,XXY KS patients were tested for autoantibodies specific to T1DM (Insulin Abs, GAD Abs, IA-2 Abs, Znt8 Abs), HT (TPO Abs), AD (21-OH Abs), and AG (APC Abs). Thirty-five of these patients were not undergoing testosterone replacement therapy TRT (Group 1) and the remaining 26 patients started TRT before the beginning of the study (Group 2). KS autoantibody frequencies were compared to those found in 122 control men. Six of 61 KS patients (9.8 %) were positive for at least one endocrine autoantibody, compared to 6.5 % of controls. Interestingly, KS endocrine immunoreactivity was directed primarily against diabetes-specific autoantigens (8.2 %), with a significantly higher frequency than in controls (p = 0.016). Two KS patients (3.3 %) were TPO Ab positive, whereas no patients were positive for AD- and AG-related autoantigens. The autoantibody endocrine profile of untreated and treated KS patients was not significantly different. Our findings demonstrate for the first time that endocrine humoral immunoreactivity is not rare in KS patients and that it is more frequently directed against type 1 diabetes-related autoantigens, thus suggesting the importance of screening for organ-specific autoimmunity in clinical practice. Follow-up studies are needed to establish if autoantibody-positive KS patients will develop clinical T1DM.

Evaluation of uncertainty of measurement from method validation data: an application to the simultaneous determination of retinol and alpha-tocopherol in human serum by HPLC.

An isocratic RP-HPLC method for the determination of retinol and alpha-tocopherol in serum, with fluorescence and UV/VIS detection, respectively, was developed and validated according to international guidelines. Detection (retinol 0.015 mg/L, alpha-tocopherol 0.29 mg/L) and quantification (retinol 0.05 mg/L, alpha-tocopherol 0.95 mg/L) limits were determined. Repeatability was <3.3% and <2.9% and intermediate precision was <4.6% and <3.2%, for retinol and alpha-tocopherol, respectively. Certified reference materials were utilised to assess bias and guarantee traceability to SI units. Expanded uncertainties (retinol 8.9%; alpha-tocopherol 7.9%), estimated according to the EURACHEM/CITAC guide from method validation data, satisfied fit-for-purpose requirements based on biological variability.