distribution of calcium
primarily intracellular, huge reserve in bone
Calcium RDA
1000-1300 mg/d (elemental calcium)
normal range (ECF) of calcium
8.5-10.5 mg/dl, unbound is biologically active portion (45% is ionized)
corrected calcium, when to use and equation
use if alb level is <3.5 because measured value is falsely low, corrected calcium=(4-measured albumin) X 0.8 + measured calcium, if corrected calcium 8.5-10.5, assume ionized calcium WNL, if corrected calcium <8.5 assume decreased ionized calcium=hypocal
effect of acidosis on ionized ca
decreased protein binding, increase percent of ionized ca
effect of alkalosis on ionized ca
increased protein binding, decrease in ionized ca, can lead to symptomatic hypoca
hypercalcemia
>10.5 mg/dL
severe hypercalcemia
>13 mg/dL
causes of hypercal
hyperparathyroidsm(large contributor), immobiliation (primarily in children), malignancy(2nd), granulomatous disease, thyrotoxicosis, famillial, tumor secreates PTH like-substances and increases bone reabsorption or factor secreted at site of bone metastasis
drugs that can cause hypercalc
thiazides (more mild), Li, calcium supplement, excess antacids, vit D intox, Vit A toxicity, tamoxifen
primary role of Vit D in regards to calcium homeostasis
increases Ca absorption in sm int
primary role of PTH in regards to ca homeostasis
increase bone resorption and the release of Ca and phosphate
signs and sx of hypercalcemia
stones, bones, abd moans and psychic groans, sx usually seen when more than or equal to 13, with malignancy more severe sx
renal stones
nephrolithiasis, poluria, dehydration, acute renal failure (precipitation of ca and phos)
NM "psychic groans
impaired conc and memory, confusion, stupor, coma, lethargy and fatigue, muscle weakness
skeleton "bones
bone pain, joint pain
CV-sx with hypercal
HTN, shortened QT interval on ECG, bradarr, vascular calcification
GI "abdominal moans
NV, anor, wt loss, consipation, abd pain, pancreatitis
other sx of hypercalc
itching keratitis, conjunctivitis
backbone of treatment of hypercalcemia
0.9% NaCl- 200-300 ml/hr IV inf, rapid onset, rehydration and dilutes Ca, increases excretion, AE: volume overload, decrease potassium, decrease Ca by 2-3 mg/dl within 24-48 hrs when used with a diureticfurosemide: 40-80 mg IV q 1-4 hrs, onset within 4 hrs, increased excretion, AE: vol deplation, decrease pot and mg, use only after rehydrated, prevents renal reabsorption of Calcium
bisphosphonates for hypercalc
zoledronate is more potent q 4-5 wks vs 30 days, 2nd choice for all, primary for malignacy, onset 24-48 hours
calcitonin for hypercalc
works faster than bis, but requires a test dose, tolerance can develop-rebound increase in ca
GCs for hypercalc
inhibitss vit D2 conv to D3(active) and decreases bone turnover, effective for hematologic malignancies and vit A and D toxicity
plicamycin
for hypercalc-used for pts refractory to other tx, need a central IV line, cytotoxic to osteoclasts, lots of AEs
Mild hypercal <13 mg/dl, asymptomatic
probably would not tx
mild ca<13mg/dL, symptomatic hypercalc
NS with loop diuretic
severe hypercalc >=13 mg/dl with or w/out sx
NS plus loop + bis(or other)
monitoring of tx of hypercalc
serum ca, UOP, EKG, VS
hypocalcemia
corrected calc <8.5 or ionized ca <4.0mg/dl
increased loss of ca from ECF-hypocalc
extravascular deposition-chronic hyperphosphatemia (CKD), acute pancreatitis, hungry bone syndrome, intravascular binding-IV phosphorus, foscarnet, hypercalciuria(loop diuretics)
decreased entry of ca into ECF-hypocalc
hypopara, decreased prod or action of vit D(nutritional, phenytoin, barbiturates, steroids), hypomg(decreased dPTH secretion or PTH resistance), Bisphos, calcitonin, cinacalcet
acute neurologic presentations of hypocalc
tetany, perioral paresthesias(numbness around mouth), carpopedal spasms, muscle spasms, cramps, pos chvostek's , pos trousseau's
acute CV sx of hypocalc
similar to ca channel blocker:prolonged QT interval, acute myocardial failure, HOTN, brady
chronic CNS sx of hypocalc
Irritabilitym memory loss, dep, conf, halluc, seizures
chronic skin sx of hypocalc
hair loss, brittle, grooved nails, eczema, psoriasis, hyperpig
tx of acute symptomatic hypocalc (based on previous)
ELEMENTAL calcium 100-300 mg slow IV(5-10 min) until tetany resolves, calc gluc -preferred-(4.65 mEq or about 93 mg elemental ca/gm OR calc chloride (13.6mEq or 273 mg elemental calc/gmfollowed by cont inf, in 1 L bag, of elemental calc at 0.5-2 mg/kg/hrmonitor serum calcium q 4-6 hrs(should return to normal in 4-6) and adjust inf rate accordingly, target calcium is low end of normal
tx for asymptomatic or chronic hypocalc
oral calcium salts, carbonate requires acid(tk with meals-most common form, caution in elderly and if on PPIs or H2)only 30-40% absorbed, to increase abs: tk with food, divide into doses <=500mg, add vit D 200-800 IU/day, citrate does not req aicd
hypocalcemia asociated with vit D deficiency
vit D+ca supplementation
ADRs of calcium supplementation
constipation, potentially kidney stones
rocaltrol, calcitrol
already in active form-if underlying kidney fxn
ergocalciferol and cholcalciferol
most common forms of vit d