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Vitamin D deficiency is typically diagnosed by measuring the concentration of the 25-hydroxyvitamin D in the blood, which is the most accurate measure of stores of vitamin D in the body. [1][7][2] One nanogram per millilitre (1 ng/mL) is equivalent to 2.5 nanomoles per litre (2.5 nmol/L). Severe deficiency: <12 ng/mL = <30 nmol/L[2] Deficiency ...
PTH is secreted primarily by the chief cells of the parathyroid glands. The gene for PTH is located on chromosome 11. It is a polypeptide containing 84 amino acids, which is a prohormone. It has a molecular mass around 9500 Da. [6] Its action is opposed by the hormone calcitonin. There are two types of PTH receptors.
A diet insufficient in vitamin D, combined with inadequate sunlight exposure, can lead to vitamin D deficiency, which is defined as a blood 25-hydroxyvitamin D or 25(OH)D level below 12 ng/mL (30 nmol/liter). Vitamin D insufficiency, on the other hand, is characterized by a blood 25(OH)D level between 12–20 ng/mL (30–50 nmol/liter).
Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. [1][4] This occurs from a disorder either within the parathyroid glands (primary hyperparathyroidism) or as response to external stimuli (secondary hyperparathyroidism). [1] Symptoms of hyperparathyroidism are caused by inappropriately normal or elevated blood ...
proteins. 25-Hydroxyvitamin D 1-alpha-hydroxylase (VD 1A hydroxylase) also known as calcidiol 1-monooxygenase[ 5 ] or cytochrome p450 27B1 (CYP27B1) or simply 1-alpha-hydroxylase is a cytochrome P450 enzyme that in humans is encoded by the CYP27B1 gene. [ 6 ][ 7 ][ 8 ] VD 1A hydroxylase is located in the proximal tubule of the kidney and a ...
CYP2R1 is cytochrome P450 2R1, an enzyme which is the principal vitamin D 25-hydroxylase. [5] [6] In humans it is encoded by the CYP2R1 gene located on chromosome 11p15.2. [7]It is expressed in the endoplasmic reticulum in liver, where it performs the first step in the activation of vitamin D by catalyzing the formation of 25-hydroxyvitamin D. [8]
Parathyroid hormone-related protein (PTHrP) is a proteinaceous hormone and a member of the parathyroid hormone family secreted by mesenchymal stem cells. It is occasionally secreted by cancer cells (for example, breast cancer, certain types of lung cancer including squamous-cell lung carcinoma). However, it also has normal functions in bone ...
Vitamin D toxicity. Cholecalciferol (shown above) and ergocalciferol are the two major forms of vitamin D. Specialty. Endocrinology, toxicology. Vitamin D toxicity, or hypervitaminosis D, is the toxic state of an excess of vitamin D. The normal range for blood concentration in adults is 20 to 50 nanograms per milliliter (ng/mL).