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74 Cards in this Set
- Front
- Back
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How much Calcium is in bone? In plasma?
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99%, 1%
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What is the reference range for Calcium?
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2.2 - 2.6 mmol/L
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What percent of Calcium in the plasma is ionized (free)?
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50%
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What percent of calcium in the plasma is protein-bound?
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40%
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What percent of calcium in the plasma is complexed with phosphate, bicarbonate and citrate?
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10%
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Which form of Calcium is biologically active?
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Ionized (free)
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Which form of Calcium is biologically inactive and not excreted?
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Protein-bound
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___________ binds calcium loosely, therefore acts as a circulating reservoir
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Albumin
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H+ and Ca++ compete for the same binding sites on albumin which means...
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Acidosis causes a release of calcium from albumin which causes hypercalcemia
Alkalosis causes opposite effect |
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A decrease in albumin causes...
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decrease in conc. of bound Ca
decrease in conc of total Ca No change in conc of active ionized Ca |
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Non ionized Calcium salts are filtered by the ________ and cannot be reabsorbed; lost in urine
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Kidney
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Intracellular calcium, although found in small amounts, plays a major role in _______, __________, _________, _____________, and _____________ .
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muscle contraction, glycogen metabolism, hormone secretion, blood hemostasis, and enzyme activation
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What hormones regulate Calcuim?
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Parathyroid Hormone (PTH), Vitamin D, Calcitonin
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Of the hormones that regulate Calcuim, Which two are the major contributors?
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Parathyroid hormone (PTH), Vitamin D
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Vitamin D is Synthesized from cholesterol making it a ________________.
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Steroid
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What are the tissues involved in Vitamin D synthesis?
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Skin, Liver, Kidney
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What are the target organs for vitamin D?
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gut, Intestine, bone, parathyroid
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What is the active form of Vitamin D?
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1, 25 (OH)2 Vitamin D
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What stimulates the production of 1alpha Hydroxylase in the kidney?
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PTH
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When is PTH produced by the parathyroid
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when calcium levels are low.
Decrease calcium causes increase in PTH production which increases Vitamin D which increases calcium reabsorption |
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What is the function of 1,25 dihydroxychoecalciferol (DHCC) or active Vitamin D?
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Required by the transmembrane proteins (in intestine and PCT) that absorb calcium and phosphorus to increase absorption
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What does an active vitamin D deficiency cause?
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Ricketts in children
Osteomalacia in adults |
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What is the sole function of the parathyroid gland?
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produce PTH and protect against hypocalcimia
Again, responds to blood calcium. |
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Decreased Ionized calcium causes a decrease in what?
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PTH
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What does PTH do?
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Enhances osteoclast activity in bone which causes, release of ionized calcium and phosphorous into plasma, which increases renal tubular reabsorption of Ca
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What is the net effect of calcium regulation by PTH
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Increases serum ionized calcium
Decrease serum ionized phosphorus Increase urine ionized phosphorus No more PTH produced (negative feedback) |
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Vitamin D reabsorbes both _______ and _______.
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Calcium, Phosphorus
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PTH only reabsorbs __________.
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Calcium
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PTH and Calcitonin are what kind of hormones?
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Peptide
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Where is calcitonin produced?
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parafollicular cells or c-cells of the thyroid gland
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Calcitonin is stimulated by ____________.
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Increase of Calcium
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What is the function of Calcitonin?
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Inhibits osteoclast activity in bones, which causes net synthesis of bone which causes removal of ionized calcium from plasma (negative feedback)
Inhibits tubular reabsorption of Ionized Calcium and enhances renal excretion of ionized calcium |
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What hormone causes ionized calcium levels to fall and where is it secreted from?
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Calcitonin, Thyroid
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What hormone causes ionized calcium levels to rise and where is it secreted from?
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PTH, Parathyroid
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What parameters are measured during parathyroid evaluation?
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Serum ionized calcium and total calcium
Ionized Phosphorus Bone ALP (or total ALP) N-terminal PTH |
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In the blood stream, ___________________% of calcium is in the biologically active ionized calcium form.
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50%
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PTH acts on bone and kidney to ____________ serum calcium concentrations
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Increases
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PTH causes increased formation of __________.
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1,25 Dihydroxy Vitamin D
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Calcitonin guards against increased calcium. (T/F)
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True
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What are symptoms of hypercalcemia
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gastrointestinal symptoms, neurologic changes, coma
Could produce kidney stones, or osteopenia |
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What is the most frequent cause of hypercalcemia?
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Primary Hyperparathyroidism
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Causes of hypocalcemia include ________.
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hypoparathyroidism, pseudohypoparathyroidism, vitamin D deficiency, renal tubular diseases, acute renal failure, gastrointestinal malabsorption and acute pancreatitis.
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What are some signs and symptoms of hypocalcemia?
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tetany, spasms, and convulsions
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What is primary hyperparathyroidism caused by?
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Adenoma or hyperplasia of the parathyroid gland
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What is the pathophysiology of primary hyperparathyroidism?
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limited of no PTH response to negative feedback, which causes breakdown of bone, which causes increase calcium but also inhibits ionized phosphorus by PCT
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What is the result of primary hyperparathyroidism?
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Increased calcium, decreased ionized phosphorus, increased ALP (Bone), Increased urine Ca and Ionized Phosphorus, increased PTH
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What is ectopic (tumor producing) PTHrP hyperparathyroidism?
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When PTHrP bind to PTH's receptors and does not respond to negative feedback. (causes increased calcium, decreased phosphorus, increased urine calcium and phosphorus)
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PTHrP
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PTH related protein, produced by cancer cells that cause hypercalcemia - any cancer
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What is secondary hyperparathyroidism?
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Parathyroid is healthy, High PTH due to secondary problem like hypocalcemia from drugs, CHRONIC RENAL DISEASE, Vitamin D deficiency, intestinal malabsorption
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What is chronic renal disease?
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Increased Pi as a result of inefficient excretion.
Decreased CaI due to decreased reabsorption. Increased PTH in response to Ca Increased ALP Decreased Vitamin D due to reduced sysnthesis as a result of inadequate renal mass. Decreased Protein and Albumin Symptoms of hyperparathyroidism |
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How does acute pancreatitis cause abnormal calcium levels?
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Causes acute hypocalcemia due to release of fatty acids which bind Ca. Decreased Ca absorption due to malabsorption results in increased PTH.
PTH responds to hypocalcemia (secondary hyperthyroid problem) |
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What is chronic hypomagnasemia?
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Causes acute hypocalcemia. Chronic Mg deficiency inhibits PTH secretion across the parathyroid gland membrane, impairs PTH action to its receptor site on bone and causes vitamin D resistance.
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What can a deficiency in Vitamin D cause?
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Secondary hyperparathyroidism
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What is the net effect of Vitamin D deficiency?
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Decreased Calcium, Decreased Phosphorus, increased ALP. Increased PTH
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What are some causes of primary hypoparathyroidism?
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It's hyposecretion of PTH. Removal of parathyroid gland, trauma, radiation therapy or thyroid, head or neck surgery
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What are symptoms of primary hypoparathyroidism?
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Tetany (musle spasms), drying skin, brittle hair, hypotension and GI upset
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What are lab results for primary hypoparathyroidism?
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Decreased Calcium, Increased phosphorus, and decreased PTH
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What is pseudohypoparathyroidism
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Inherited tubular resistance to biological activity (defect in signaling of the receptor) of PTH
Increased PTH is produced as a result of hypocalcemia but cannot respond to Ca. |
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What is the pathophysiology of pseudohypoparathyroidism?
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Increased Phosphorus, Decreases Calcium Which stimulates increased PTH which cause bone breakdown to restore Calcium and decreases phosphorus in the urine
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What is the net product of pseudohypoparathyroidism?
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serum has borderline decreased calcium, increased phosphorus, increased ALP, PTH is normal to increased, Vit D also decreased due to lack of PTH response.
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What is Paget's disease?
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hyperactivity of osteoclasts which results in the constant remodeling of bone causing thick and misshapen bone surfaces
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What is the result of a tumor pressing on bone?
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Breakdown and release of Ca and P. Increase in Ca causes inhibition of PTH and no stimulus to get rid of extra phosphorus
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The is the net result of primary bone disorders?
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Increased Calcium
Increased phosphorus Increased ALP Decreased PTH Bone had decalcified holes |
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What causes osteoporosis?
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Aging or inactivity
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What is osteoporosis?
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Reduction in bone mass (break bown of collagen)
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What compound can be measured and when increased suggests osteoporosis?
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Increased pyridinoline in urine
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Is osteoporosis a secondary parathyroid disease?
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No. PTH is normal
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What are the methods for measuring calcium?
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Ion Selective Electrode (ionized Ca), Dye binding method (Total Ca), AAS (reference method)
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What is the membrane for calcium ISE?
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octyl-phenyl-phosphonate
Measured potentiometrically |
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What reactions occur in dye binding method?
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Dye- + Ca2+ ------> colored dye-Ca complex
Ca2+ + Ca-albumin + Ca-salt + dye ------> dye-complex + albumin + salt- |
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What is the reference method for measuring calcium?
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Atomic absorption spectroscopy
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What is the reference range for total calcium?
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8.6 - 10.0 mg/dL adults
8.6 - 10.6 mg/dL children |
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What gland regulates phosphates?
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parathyroid gland via PTH
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What hormones regulate phosphorus?
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vitamin D, Calcitriol
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