34 HYPERCALCEMIA General Discussion The three pathophysiological mechanisms for hypercalcemia are increased bone resorption, increased gastrointestinal absorption of calcium, and decreased renal excretion of calcium. Increased bone resorption accounts for most cases of hypercalcemia and is seen in both primary hyperparathyroidism and malignancy. Increased gastrointestinal absorption of calcium usually is mediated by vitamin D through an increase in the production of 1,25 dihydroxyvitamin D, a mechanism seen in lymphomas and granulomatous disease. Decreased renal excretion of calcium is rare but may be caused by medications such as diuretics and lithium that affect the renal handling of calcium. Concentrations of calcium are highly modulated through the actions of parathyroid hormone (PTH), calcitonin, and vitamin D acting on target organs such as bone, kidney, and the gastrointestinal tract. Primary hyperparathyroidism represents the leading cause of hypercalcemia, and malignancy is the second leading cause. Together, they account for more than 90% of the cases of hypercalcemia. Primary hyperparathyroidism is usually caused by a single adenoma of the parathyroid gland. Glandular hyperplasia, multiple adenomas, and parathyroid malignancy are less common. The hypercalcemia of malignancy is caused by increased bone resorption from skeletal metastases or the production of parathyroid hormone related peptide (PTHrP) that stimulates osteoclasts. Since low albumin levels can affect the total calcium level, the evaluation of hypercalcemia begins with the calculation of the corrected calcium level using the following formula: If the patient is on any medications known to be associated with hypercalcemia, the causative medications should be stopped and the calcium levels rechecked. If the patient is not on any of these medications or if the calcium level remains high, the work-up for hypercalcemia may begin. The serum PTH level helps guide the evaluation of hypercalcemia. PTH is elevated in primary hyperparathyroidism and suppressed in malignancy-associated hypercalcemia. The remainder of the diagnostic evaluation is outlined below. Medications and Ingestions Associated with Hypercalcemia Betel nuts Calcium Calcium and vitamin D (milk alkali syndrome) Dialysate calcium Ganciclovir Growth hormone therapy Lithium Manganese Parenteral nutrition Tamoxifen Theophylline Thiazide diuretics Thyroid hormone excess Vitamin A Vitamin D Causes of Hypercalcemia Endocrine/metabolic disorders • Familial hypocalciuric hypercalcemia • Hyperthyroidism • Hypoadrenalism • Hypophosphatasia • Lactase deficiency • Multiple endocrine neoplasia types I and IIa • Pheochromocytoma • Primary hyperparathyroidism • Vipoma • William’s syndrome Granulomatous disease • Bartonella (cat-scratch disease) • Berylliosis • Blastomyces • Candidiasis • Coccidioidomycosis • Cryptococcus • Cytomegalovirus Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: ARTHRITIS AND ARTHRALGIA HAIR LOSS HYPOTHYROIDISM TRANSAMINASE ELEVATION Stay updated, free articles. Join our Telegram channel Join Tags: Instant Work-ups A Clinical Guide to Medicine Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off on HYPERCALCEMIA Full access? Get Clinical Tree
34 HYPERCALCEMIA General Discussion The three pathophysiological mechanisms for hypercalcemia are increased bone resorption, increased gastrointestinal absorption of calcium, and decreased renal excretion of calcium. Increased bone resorption accounts for most cases of hypercalcemia and is seen in both primary hyperparathyroidism and malignancy. Increased gastrointestinal absorption of calcium usually is mediated by vitamin D through an increase in the production of 1,25 dihydroxyvitamin D, a mechanism seen in lymphomas and granulomatous disease. Decreased renal excretion of calcium is rare but may be caused by medications such as diuretics and lithium that affect the renal handling of calcium. Concentrations of calcium are highly modulated through the actions of parathyroid hormone (PTH), calcitonin, and vitamin D acting on target organs such as bone, kidney, and the gastrointestinal tract. Primary hyperparathyroidism represents the leading cause of hypercalcemia, and malignancy is the second leading cause. Together, they account for more than 90% of the cases of hypercalcemia. Primary hyperparathyroidism is usually caused by a single adenoma of the parathyroid gland. Glandular hyperplasia, multiple adenomas, and parathyroid malignancy are less common. The hypercalcemia of malignancy is caused by increased bone resorption from skeletal metastases or the production of parathyroid hormone related peptide (PTHrP) that stimulates osteoclasts. Since low albumin levels can affect the total calcium level, the evaluation of hypercalcemia begins with the calculation of the corrected calcium level using the following formula: If the patient is on any medications known to be associated with hypercalcemia, the causative medications should be stopped and the calcium levels rechecked. If the patient is not on any of these medications or if the calcium level remains high, the work-up for hypercalcemia may begin. The serum PTH level helps guide the evaluation of hypercalcemia. PTH is elevated in primary hyperparathyroidism and suppressed in malignancy-associated hypercalcemia. The remainder of the diagnostic evaluation is outlined below. Medications and Ingestions Associated with Hypercalcemia Betel nuts Calcium Calcium and vitamin D (milk alkali syndrome) Dialysate calcium Ganciclovir Growth hormone therapy Lithium Manganese Parenteral nutrition Tamoxifen Theophylline Thiazide diuretics Thyroid hormone excess Vitamin A Vitamin D Causes of Hypercalcemia Endocrine/metabolic disorders • Familial hypocalciuric hypercalcemia • Hyperthyroidism • Hypoadrenalism • Hypophosphatasia • Lactase deficiency • Multiple endocrine neoplasia types I and IIa • Pheochromocytoma • Primary hyperparathyroidism • Vipoma • William’s syndrome Granulomatous disease • Bartonella (cat-scratch disease) • Berylliosis • Blastomyces • Candidiasis • Coccidioidomycosis • Cryptococcus • Cytomegalovirus Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: ARTHRITIS AND ARTHRALGIA HAIR LOSS HYPOTHYROIDISM TRANSAMINASE ELEVATION Stay updated, free articles. Join our Telegram channel Join Tags: Instant Work-ups A Clinical Guide to Medicine Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off on HYPERCALCEMIA Full access? Get Clinical Tree
