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| ==Causes==
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| Hypocalcemia can be the consequence of multiple disease processes, some of which will be mentioned in the following discussion. The most common cause is the inability to mobilize calcium from bone which is primarily induced by decreased levels of the parathyroid hormone (PTH) due to derangement of the parathyroid gland function (ie, the gland responsible of calcium homeostasis) or vitamin D deficiency.
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| * Hypoparathyroidism: It signifies diminished activity of the parathyroid gland due to multiple reasons: autoimmune destruction (included in the polyglandular autoimmune syndrome type I), resection of the glands as a possible complication of total thyroidectomy or genetic diseases affecting the gland's function. A second entity that should be mentioned is pseudohypoparathyroidism which is characterized by normal gland function but inability of the PTH-target organs (bone and kidney) to respond to PTH. Patients present with hypocalcemia but high PTH levels.
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| ==Complete Differential Diagnosis of the Causes of Hypocalcemia==
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| (In alphabetical order)
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| * Absent active [[vitamin D]]
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| * Absent [[parathyroid hormone]] (PTH)
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| * Acquired [[hypoparathyroidism]]
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| * [[Acute pancreatitis]]
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| * [[Acute renal failure]]
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| * [[Adrenocortical hyperplasia]]
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| * [[Alcohol abuse]]
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| * [[Alkalosis]]
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| * [[Anticonvulsant]] therapy
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| * [[Breast cancer]]
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| * [[Bronchial cancer]]
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| * [[Burns]]
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| * [[Chelation]] therapy
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| * [[Chronic renal failure]]
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| * [[Cirrhosis]]
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| * Decreased dietary intake
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| * Decreased [[ultraviolet]]/sun ([[vitamin D deficiency]])
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| *Defective [[Vitamin D]] metabolism
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| * Deficient [[PTH]]
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| * [[DiGeorge's syndrome]]
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| * [[Diuretic]] therapy
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| * [[Drugs]]
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| * [[Eating disorders]]
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| * [[Enemas]], [[laxative]]s
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| * Enhanced [[bone]] formation
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| * Excessive secretion of calcitonin
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| * Exposure to [[hydrofluoric acid]]
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| * [[Familial hypocalcemia]]
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| * Following [[thyroidectomy]]
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| * Hereditary [[hypoparathyroidism]]
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| * "Hungry Bone Syndrome" following [[parathyroidectomy]],
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| * [[Hyperphosphatemia]]
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| * [[Hyperventilation]].
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| * [[Hypoalbuminemia]] (pseudohypocalcemia)
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| * [[Hypomagnesemia]]
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| * [[Hypoparathyroidism]]
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| * [[Hypoproteinemia]]
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| * Increased [[diuresis]] with physiologic saline solution
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| * Intestinal [[malabsorption]]
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| * Intravenous phosphate administration
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| * Kidney diseases with reduced formation of activated [[vitamin D]]
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| * [[Magnesium]] depletion
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| * [[Magnesium]] over supplementation
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| * [[Malabsorption]]
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| * Mal[[digestion]]
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| * [[Medullary carcinoma of the thyroid]]
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| * Neonatal [[tetany]]
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| * [[Nephrotic syndrome]]
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| * [[Osteitis fibrosa]] following [[parathyroidectomy]]
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| * Osteoblastic metastases
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| * [[Osteoporosis]]
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| * [[Pancreatitis]]
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| * Polyglandular [[autoimmune]] syndrome
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| * Postoperative
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| * Prolonged use of medications/laxatives containing [[magnesium]]
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| * [[Pseudohypoparathyroidism]]
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| * [[Renal failure]]
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| * [[Rhabdomyolysis]]
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| * [[Rickets]]
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| * [[Sepsis]]
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| * [[Septic shock]]
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| * Severe acute [[hyperphosphatemia]]
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| * [[Short bowel syndrome]]
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| * [[Steroid]] therapy
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| * [[Thyroid cancer]]
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| * [[Transfusion]] of citrated blood
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| * [[Tumor lysis syndrome]]
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| * [[Vitamin D deficiency]]
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| * Vitamin-D dependent [[rickets]], type I
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| ===Complete Differential Diagnosis of the Causes of Hypocalcemia===
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| (By organ system)
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| {|style="width:80%; height:100px" border="1"
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| |style="height:100px"; style="width:25%" border="1" bgcolor="LightSteelBlue" | '''Cardiovascular'''
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| |style="height:100px"; style="width:75%" border="1" bgcolor="Beige" | No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Chemical / poisoning'''
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| |bgcolor="Beige"| [[Alcohol abuse]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Dermatologic'''
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| |bgcolor="Beige"| No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Drug Side Effect'''
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| |bgcolor="Beige"| [[Anticonvulsant]] therapy, [[Chelation]] therapy, [[Diuretic]] therapy, [[Drugs]], [[Enemas]], [[laxative]]s, [[Steroid]] therapy
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Ear Nose Throat'''
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| |bgcolor="Beige"| No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Endocrine'''
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| |bgcolor="Beige"| Absent [[parathyroid hormone]] (PTH), Acquired [[hypoparathyroidism]], [[Adrenocortical hyperplasia]], Deficient [[PTH]], Excessive secretion of calcitonin, [[Familial hypocalcemia]], Following [[thyroidectomy]], Hereditary [[hypoparathyroidism]], "Hungry Bone Syndrome" following [[parathyroidectomy]], [[Hypoparathyroidism]], [[Hypoproteinemia]], [[Medullary carcinoma of the thyroid]], [[Osteitis fibrosa]] following [[parathyroidectomy]], [[Osteoporosis]], [[Pseudohypoparathyroidism]], [[Thyroid cancer]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Environmental'''
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| |bgcolor="Beige"| Decreased [[ultraviolet]]/sun ([[vitamin D deficiency]]), Defective [[Vitamin D]] metabolism, Exposure to [[hydrofluoric acid]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Gastroenterologic'''
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| |bgcolor="Beige"| [[Acute pancreatitis]], [[Cirrhosis]], Decreased dietary intake, [[Eating disorders]], [[Enemas]], [[laxative]]s, Intestinal [[malabsorption]], [[Malabsorption]], Mal[[digestion]], [[Pancreatitis]], [[Rickets]], [[Short bowel syndrome]], Vitamin-D dependent [[rickets]], type I
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Genetic'''
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| |bgcolor="Beige"| [[DiGeorge's Syndrome]], [[Familial hypocalcemia]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Hematologic'''
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| |bgcolor="Beige"| [[Hypoalbuminemia]] (pseudohypocalcemia), [[Transfusion]] of citrated blood, [[Tumor lysis syndrome]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Iatrogenic'''
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| |bgcolor="Beige"| No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Infectious Disease'''
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| |bgcolor="Beige"| [[Sepsis]], [[Septic shock]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Musculoskeletal / Ortho'''
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| |bgcolor="Beige"| Enhanced [[bone]] formation, Excessive secretion of calcitonin, Neonatal [[tetany]], [[Osteitis fibrosa]] following [[parathyroidectomy]], [[Osteoporosis]], [[Rickets]], Vitamin-D dependent [[rickets]], type I
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Neurologic'''
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| |bgcolor="Beige"| No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Nutritional / Metabolic'''
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| |bgcolor="Beige"| Absent active [[vitamin D]], Decreased dietary intake, [[Hyperphosphatemia]], Intestinal [[malabsorption]], Intravenous phosphate administration, [[Magnesium]] depletion, [[Rickets]], [[Vitamin D deficiency]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Obstetric/Gynecologic'''
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| |bgcolor="Beige"| [[Breast cancer]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Oncologic'''
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| |bgcolor="Beige"| [[Breast cancer]], [[Bronchial cancer]], [[Medullary carcinoma of the thyroid]], Osteoblastic metastases, [[Thyroid cancer]], [[Tumor lysis syndrome]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Opthalmologic'''
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| |bgcolor="Beige"| No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Overdose / Toxicity'''
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| |bgcolor="Beige"| [[Magnesium]] over supplementation, Prolonged use of medications/laxatives containing [[magnesium]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Psychiatric'''
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| |bgcolor="Beige"| [[Eating disorders]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Pulmonary'''
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| |bgcolor="Beige"| [[Bronchial cancer]], [[Hyperventilation]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Renal / Electrolyte'''
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| |bgcolor="Beige"| [[Acute renal failure]], [[Alkalosis]], [[Chronic renal failure]], [[Hypomagnesemia]], [[Hypoproteinemia]], Increased [[diuresis]] with physiologic saline solution, Intravenous phosphate administration, Kidney diseases with reduced formation of activated [[vitamin D]], [[Magnesium]] depletion, [[Magnesium]] over supplementation, [[Nephrotic syndrome]], [[Renal failure]], [[Rhabdomyolysis]], Severe acute [[hyperphosphatemia]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Rheum / Immune / Allergy'''
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| |bgcolor="Beige"| [[DiGeorge's Syndrome]], [[Osteitis fibrosa]] following [[parathyroidectomy]], Polyglandular [[autoimmune]] syndrome
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Sexual'''
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| |bgcolor="Beige"| No underlying causes
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Trauma'''
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| |bgcolor="Beige"| [[Burns]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Urologic'''
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| |bgcolor="Beige"| [[Acute renal failure]], [[Chronic renal failure]], [[Hypoproteinemia]], [[Renal failure]]
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| |-
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| |-bgcolor="LightSteelBlue"
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| | '''Miscellaneous'''
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| |bgcolor="Beige"|Postoperative, [[Transfusion]] of citrated blood
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| |-
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| |}
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| == Diagnosis ==
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| === History and Symptoms ===
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| * [[Fatigue]]
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| * [[Weakness]]
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| * [[Muscle cramp]]ing and spasm
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| * [[Nausea]] and [[vomiting]]
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| * [[Abdominal pain]]
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| * [[Depression]]
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| * [[Irritability]]
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| * [[Delirium]]
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| * [[Psychosis]]
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| * [[Seizures]] (with severe hypocalcemia)
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| * [[Perioral]] tingling and [[parasthesia]], 'pins and needles' sensation over the extremities of hands and feet. This is the earliest symptom of hypocalcemia.
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| ==Signs==
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| * [[Tetany (medical sign)|Tetany]], carpopedal spasm are seen.
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| * Latent tetany
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| ** [[Trousseau sign of latent tetany]] (eliciting carpal spasm by inflating the [[blood pressure]] cuff and maintaining the cuff pressure above [[systolic]])
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| ** [[Chvostek's sign]] (tapping of the inferior portion of the [[zygoma]] will produce facial spasms)
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| * Tendon reflexes are hyperactive
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| * Life threatening complications
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| ** [[Laryngospasm]]
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| ** [[Cardiac arrhythmia]]s
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| ==Clinical Features Associated with Hypocalcemia==
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| * [[Abdominal pain]]
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| * [[Alopecia]]
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| * [[Anxiety]]
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| * [[Atopic eczema]]
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| * [[Biliary colic]]
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| * [[Brittle nails]]
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| * [[Bronchial spasm]]
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| * Calcification of cerebral cortex or cerebellum
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| * [[Cardiomyopathy]]
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| * [[Choreoathetosis]]
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| * [[Chvostek's sign]]
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| * Coarse hair
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| * [[Confusion]]
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| * [[Congestive heart failure]]
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| * Delayed tooth eruption
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| * Disorientation
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| * [[Dry skin]]
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| * [[Dysphagia]]
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| * [[Dyspnea]]
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| * Dystonic spasms
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| * Enamel hypoplasia
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| * Exfoliative dermatitis
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| * Extrapyramidal signs due to calcification of basal ganglia
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| * [[Fatigue]]
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| * Impaired intellectual ability
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| * Impetigo herpetiformis
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| * Increased dental caries
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| * Increased intracranial pressure
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| * [[Irritability]]
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| * [[Laryngeal spasm]]
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| * [[Muscle cramp]]s
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| * Nonspecific EEG changes
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| * [[Papilledema]]
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| * [[Paresthesia]]
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| * [[Parkinsonism]]
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| * Personality disturbances
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| * [[Polymyositis]]
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| * Prolonged QT interval in EKG
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| * [[Psoriasis]]
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| * [[Psychoneurosis]]
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| * [[Psychosis]]
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| * [[Seizure]]s (focal, petit mal, grand mal)
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| * Shortened premolar roots
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| * Subcapsular cataracts
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| * [[Tetany]]
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| * Thickened lamina dura
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| * [[Trousseau's sign]]
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| * [[Wheezing]]
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| ==Electrocardiographic Findings==
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| # Prolongation of the [[QTc interval]] is the major EKG finding
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| # There is a lengthening of the interval between the end of the [[QRS]] and the beginning of the [[T wave]] (i.e. [[ST-segment]] lengthening).
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| ==EKG examples==
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| [[image:Hypocalcemia_ProlongedQT.jpg|thumb|left|300px|Prolonged QTc interval due to hypocalcemia]]
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| <br clear="left"/>
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| ==Management== | | ==Management== |