{'fraction_non_alphanumeric': 0.03077716643741403, 'fraction_numerical': 0.014614855570839065, 'mean_word_length': 5.194888178913738, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 2, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Vitamin D toxicity – causes, symptoms and diagnosis

: Introduction and purpose: This review aims to analyze causes, symptoms and diagnosis of overdosing vitamin D resulting in vitamin D toxicity (VDT). Material and method: This paper was based on medical articles collected in Pubmed from 2008 to 2021 year. The research has been done by looking through keywords such as “vitamin D” “toxicity”. Results: The review of studies showed that manifestation of VDT is mainly associated with hypercalcemia and its course can range from asymptomatic to life-threatening, including death. We also draw attention to inappropriate use and widespread of vitamin D products. Conclusion: There is a high demand for medical health workers to advise patients on possible effects of inappropriate use of vitamin D products and its toxicity. Medical practitioners should be attentive to quickly identify VDT.

to 2021 year. The research has been done by looking through keywords such as "vitamin D" "toxicity".
Results: The review of studies showed that manifestation of VDT is mainly associated with hypercalcemia and its course can range from asymptomatic to life-threatening, including death.
We also draw attention to inappropriate use and widespread of vitamin D products.
Conclusion: There is a high demand for medical health workers to advise patients on possible effects of inappropriate use of vitamin D products and its toxicity. Medical practitioners should be attentive to quickly identify VDT.

INTRODUCTION:
Vitamin D (cholecalciferol) is a crucial prohormone in human body that regulates calcium and phosphate homeostasis. It is mainly synthesized in the skin under UV influence.
Vitamin D undergoes two reactions -25-hydroxylation in the liver and 1-hydroxylation in the kidney to its active form 1,25-dihydroxycholecalciferol -1,25(OH)2D (calcitriol) [1]. Calcitriol influences calcium and phosphate homeostasis by increasing both phosphorus and calcium absorption from intestines [2]. Thus, vitamin D deficiency is related to lower calcium absorption resulting hypocalcemia, bone disorders and secondary hyperparathyroidism [2,3]. In compliance with the American Academy of Pediatrics (AAP) recommended intake of vitamin D for children is 400 IU per day from birth to adolescence [3]. While for adults it ranges from 600 IU to 2000 IU per day, depending on different recommendations [4]. Deficiency of vitamin D concentration is a prevalent and global problem in public health system. In the result, raising awareness of vitamin D insufficiency lead to growing intake of vitamin D supplements. However, increasing number of prescriptions with very high doses of vitamin D without medical surveillance may result in hypervitaminosis D.

CAUSES OF VDT
One of the causes of VTD are formulation and fortification errors in food manufacturing.
Some studies indicate that there are marked differences in the actual and stated doses eg. excessive fortification of vitamin D in dairy products, which lead to 56 cases (including 41 that required hospitalization and two deaths) because of VDT [2]. Secondly, there is a raising problem of inappropriate describing and dispensing. The administration of a single very large dose of vitamin D (60 000 IU and above) to treat its deficiency called stoss therapy, may expose patients to potentially dangerous side effects of misuse and overdose. Also, an inappropriate administration of vitamin D can lead to VDT as it was in 19-year-old male case admitted to 978 hospital with hypercalcemia and acute kidney injury. According to the report, he was using a parenteral mixture intended for veterinary use and containing 5 000 000 IU of vitamin D in order to develop his muscles [2,5].

SYMPTOMS OF VDT
Clinical course of vitamin D overdose may range from asymptomatic to highly-severe, including death [6]. Most common symptoms are these related to hypercalcemia. Largely, it is characterized by renal manifestation, which includes nephrocalcinosis, hypercalciuria or acute kidney injury and neuropsychiatric (psychosis, confusion, stupor or coma). It can also affect cardiovascular system causing hypertension, ST segment elevation, shortened QT interval, first degree heart block and bradyarrythmias. Last but not least are gastrointestinal problems such as abdominal pain, constipation, pancreatitis, vomiting or polidypsia [7]. Less common symptoms of VDT can be hearing loss and painful periarticular calcinosis [5]. VDT is usually characterized by elevated 25(OH)D concentration (> 150 ng/ml) with soft-tissue calcification, hypercalcemia and hypercalciuria [5,8].

DIAGNOSIS OF VDT
VDT can be diagnosed by its clinical features. An early diagnosis demands scrupulous drug and clinical history. Largely, VDT is the result of overdosage or too frequent dosage of vitamin D among patients with osteoporosis or other diseases that require vitamin D administration [5]. Beside clinical features, the diagnosis of VDT is also determined by elevated 25(OH)D concentration (> 150 ng/ml), suppressed parathormone and usually normal level 1,25(OH)D [5,8,9]. Bearing in mind, that there is a widespread use of vitamin D, it is crucial for general practitioners to be alert to the symptoms of vitamin D overdose among their patients [5].

SUMMARY
Although VDT with manifestation of hypercalcemia is infrequent, it may be also lifethreatening. There is a high need to warn patients about possible side effects of misuse of vitamin D as well as for medical practitioners to promptly identify VDT. In each case of hypercalcemia, VDT should be considered as potential diagnosis. Clear verbal and written instructions should be present for prescribed and over-the-counter vitamin D products. Moreover, patients should be advised to read and follow the recommendations carefully. Bibliography: