[A rare cause of kidney injury: vitamin D3 intoxication]. / A vesekárosodás ritka oka: D3-vitamin-intoxikáció.

The beneficial effects of vitamin D3 treatment are known, and its side effects are documented. In connection with the case presentation, we would like to sum up the dangers of excessive vitamin D supplementation, and to draw attention to the shortcomings experienced in everyday medical practice. We discuss the tests required to create a diagnosis of vitamin D intoxication, the differential diagnosis, and present the possible treatment strategies. A 57-year-old female patient was admitted to hospital in November 2020 due to complaints of nausea, vomiting, diarrhea and general weakness. Upon admission, laboratory tests confirmed new-onset kidney damage (eGFR 38 mL/min/1.73 m2), calcium metabolism was not checked. During non-invasive investigations, urinary sediment results showed leukocyturia and non-nephrotic proteinuria, but no clear underlying cause was found. Nephrology consultation suggested acute tubular injury, kidney biopsy was performed, immune serology and serum protein electrophoresis tests were ordered. Despite conservative treatment, her kidney function deteriorated further (eGFR 32 mL/d/1.73 m2). The patient arrived at our department in December 2020 with histological results in progress. Laboratory tests taken on arrival confirmed severe hypercalcemia (tCa 3.22 mmol/L, iCa 1.74 mmol/L), and kidney function was stable (eGFR 33 mL/p/1.73 m2). Intact parathyroid hormone level was below the normal range (0.54 pmol/L), 25-OH-vitamin D level was extremely high (1106.2 nmol/L). The patient then admitted that in October 2020, she received a course of "megadose" parenteral vitamin D, but she could not recall the exact dosage nor wanted to mention the department administering the treatment. We diagnosed vitamin D intoxication. Intravenous saline, furosemide and calcitonin treatment was started. The result of the treatment: serum calcium level normalized (2.52 mmol/L), and kidney functions improved (eGFR 54 mL/p/1.73 m2). Vitamin D treatment was stopped. The patients' serum tCa and vitamin D levels normalized by February 2021, and her kidney functions improved (tCa 2.54 mmol/L, 25-OH-vitamin D 125.0 ng/mL, eGFR 72 mL/p/1.73 m2). Kidney biopsy confirmed the presence of acute tubular necrosis. Granulomatous diseases and multiple myeloma were excluded. The symptoms of vitamin D intoxication are non-specific and varied, each case presents a differential diagnostic challenge. Orv Hetil. 2023; 164(47): 1871-1876.

Advanced glycation end products and their soluble receptor (sRAGE) in patients with Hashimoto's thyroiditis on levothyroxine substitution.

Background: Advanced glycation end products (AGEs) are heterogenous group of irreversible chemical moieties originated from non-enzymatic glycation and oxidation of proteins, nucleic acids, and lipids. The engagement of AGEs with their chief cellular receptor (RAGE) activates a myriad of signaling pathways contributing to the progression of chronic diseases like autoimmune thyroiditis, type 2 diabetes mellitus and its complications. Soluble RAGE (sRAGE) prevents AGE-RAGE interaction in a competitive manner. Objective: We investigated the association between serum AGE, sRAGE and thyroid function in 73 Hashimoto thyroiditis patients (HT) on levothyroxine substitution, and in 83 age, BMI and gender-matched healthy controls. Methods: The serum AGEs levels were determined by autofluorescence on a multi-mode microplate reader, and the serum sRAGE levels by ELISA method. Results: Mean AGE level was lower (10.71 vs 11.45 AU/µg protein; p=0.046), while mean sRAGE level was higher (923 vs 755 pg/mL; p<0.0005) in the serum of HT patients than the controls. AGE correlated with age, while sRAGE correlated negatively with BMI in both groups. We found negative correlation between AGE and fT3 levels (r=-0.32; p=0.006) and sRAGE and TSH levels (r=-0.27; p=0.022) in HT patients, while we failed to find association between AGE, sRAGE and parameters of thyroid function in the control group. Median AGE/sRAGE ratio was lower in HT patients than in controls (2.4, IQR 1.9 - 3.1 vs 3.3, IQR 2.3 - 4.1 AU/pg; p < 0.001). In HT patients, the AGE/sRAGE ratio correlated positively with BMI and correlated negatively with fT3. Conclusion: According to our results in HT patients lower TSH and higher fT3 levels within the reference range is accompanied by a favorable AGE/RAGE balance. Further investigations are needed to confirm these results.