patho/pct electrolytes

magnesium secretes

PTH

increased magnesium will

calm everything down

95% of filtered Mg is

reabsorbed

hypomagnesemia is considered under

1.4 mEq/L

severe hypomagnesemia is considered

below 1.0 mEq/L

lots of magnesium absorption occurs in

the intestines

medications that cause hypomagnesemia

PPIs, Mg citrate, loop and thiazide diuretics, amphotericin B, tacrolimus, cyclosporine

amphotericin B causes

renal electrolyte wasting

Symptoms of Hypomagnesemia

muscle twitches, cramps, tremors

can seizures be caused from hypomagnesemia?

yes, being LOW in Mg2+ makes the body MORE excited

cv symptoms of hypomagnesemia

Heart palps, EKG arrhythmias (peaked T and wide QRS)

signs of hypomagnesemia

Trousseau's sign

Chvostek's sign

severe hypomagnesemia treatment

IV Mg2+ sulfate

magnesium dosing is

4-6 g in 50-100 mL in divided doses over 12-24 hrs and repeat

Mg2+ suppresses

neuromuscular transmission

if Mg2+ levels get too high,

muscle weakness leads to decreased respiratory rate

Magnesium causes vaso_____

dilation

should you give magnesium to preeclamptic pts?

yes because pt is at RISK for seizures

hypermagnesemia is considered anything over

2 mEq/L

hypermagnesemia is caused by

decreased renal excretion

too high in magnesium =

depressed NS (weak, bradycardia)

symptoms of hypermagnesemia

hypotonia, coma, paralysis, respiratory depression, hypotension, arrhythmias, EKG changes, prolonged QT or PR

hypermagnesemia is symptomatic above

6 mEq/L

for symptomatic hypermagnesemia, treat by

IV calcium gluconate (peripheral) or calcium chloride (PICC)

for a hypermagensemic pt that has kidney failure, treat with

hemodialysis

for a hypermagensemic pt that has good kidneys, treat with

0.9 NS bolus AND loop diuretic

calcium is used for

Preservation and function of cell membranes

calcium is mostly found in the

bones

serum Ca exists in

3 forms

what are the 3 forms of Ca?

Protein bound to ALBUMIN (40%)

Complexed (10%)

Physiologically-active, ionized Ca2+ (50%)

Physiologically-active, ionized Ca2+ (50%) is considered the

true active form

how to find calcium correction

[(4 - alb) x 0.8] + Ca = Ca corr

when would you use the calcium correction equation

Only use if pt has an albumin LOWER than 4

Low albumin = ______ calcium because

low; because 40% of Ca is bound to albumin

Ionized calcium is REGULATED by

interactions of hormones: PTH, calcitonin, vitamin D (calcitriol)

the job of pTH is to

increase serum Ca

When Ca falls, PTH is

secreted

secreting PTH, will _______ Ca via

release; breaking down the bone

daily Ca2+ requirements

1000-1200 mg per day

neonates need more

vitamin D

hypocalcemia is considerded

lower than 8.5 mEq/L

hypocalcemia is associated with

hypoparathyroidism, vitamin D deficiency, severe hypomagnesemia

medications inducing hypocalcemia

Loop diuretics, calcitonin, cinaclacet, phosphate, Phenobarbital, phenytoin, ketoconazole

Vitamin D deficiency = ____________ in Ca2+ reabsorption

DECREASE

symptoms of hypocalcemia

Tetany, muscle cramps, seizures

Hypotension, arrhythmias, EKG changes (increased QT interval)

Dry, puffy; eczema, psoriasis

signs of hypocalcemia

Trousseau's sign

Chvostek's sign

first thing to do for treatment of a hypocalcemic pt is

Check if its REAL or if its hypoalbuminemia (Ca corr equation)

if the pt is found to have true hypocalcemia, then

give calcium gluconate

if pt has serum ca of 1-1.09 mEq/L, then give

ca gluconate 3 g in 80 mL NS over 30 min

if pt has serum ca of LOWER than 1 mEq/L, then give

Ca gluconate 3 g in 80 mL NS over 30 and notify MD

treat hypocalcemic pt if Ca corr is below

8.6 or ionized Ca is LOWER than 4.4

Chronic asymptomatic hypocalcemic pts are treated with

ORAL REPLACEMENT (1-3 g per day)

DO NOT EXCEED ________ of elemental Ca/minute

30-60 mg

calcium replacement adverse effects

Hypercalciuria (pts with hypoPTH)

Renal calcium stones

Check renal calcium excretion

hypercalcemia is considered over

10.5 mEq/L

severe hypercalcemia is considered over

12 mEq/L

hypercalcemia is associated with

cancer, hyperparathyroidism, granulomatous disease

medications inducing hypercalcemia

thiazides, vitamin D, Ca2+ supplements, lithium, tamoxifen, ganciclovir

symptoms of severe hypercalcemia

Nephrolithiasis, CDK, EKG changes (Decreased QT interval), HTN, coma, severe constipation

symptoms of mild/moderate hypercalcemia

Fatigue, weak, depression, constipation

ways to reduce calcium levels for hypercalcemic pts

Increase renal Ca elimination

Inhibit Ca resorption from bone

Interfere with GI absorption

Decrease GI absorption

Decrease sensitivity of calcium sensing receptor

treating symptomatic hypercalcemia

1. NS 0.9%

2. loop diuretic

3. calcitonin

4. glucocorticoids

calcitonin is the opposite of

PTH

calcitonin inhibits

osteoclasts; less bone breakdown, less ca released

Importance of kidney function in hypercalcemic pts?

All early treatment RELIES on kidneys REMOVING Ca

Calcitonin, glucocorticoids, bisphos all inhibit

Ca resorption from BONE (usually for pts with osteoporosis)

Cinacalcet works by

tricking PTH into thinking there is MORE ca in the blood then there is

major AE of cinacalcet

hypocalcemia due to OVERCORRECTION from working too well; vomiting as well

phosphorus is good for

energy

if phosphorus is low, then your body responds by

going slow and shutting down

phosphorus is higher in

children due to active bone growth

severe hypophosphatemia is considerded below

1 mEq/L

mild/moderate hypophosphatemia is

1-2 mEq/L

associated with hypophosphatemia is

decreased GI absorption, increased urinary excretion, internal redistribution

symptoms of acute hypophosphatemia are

Metabolic encephalopathy syndrome, decreased contractility, respiratory failure, heart failure

symptoms of chronic hypophosphatemia are

Rickets, osteomalacia, osteopenia

treatment for asymptomatic hypophosphatemia

Oral Na+ or K+ phos salts

important counseling point for hypophosphatemia

Osmotic diarrhea is COMMON

dietary phosphate is recommended as

1 cup or 8 mmol

for symptomatic or severe hypophosphatemia, pt should be given

Initial bolus of Na+ PHos or K+ Phos over 4-6 hours

for symptomatic or severe hypophosphatemia, pt should be given as maintenance

Add Na+ phos or K+ phos to IV fluids

hyperphosphatemia is considered over

4.5 mEq/L

associated with hyperphosphatemia is

Decreased GFR, Latrogenic, Rhabdomyolysis

symptoms of hyperphosphatemia are

Nephrolithiasis (kidney stones)

N/V, diarrhea, lethargy, seizures, tetany

Ca2+/Phos ratio: Ca2+ x phos

how to manage hyperphosphatemia?

Phosphate-binding antacids (ca carbonate), stop exogenous Phos, limit in diet, NS + diuretic

Sevelamar is an

expensive medication, used only for pts that have hypercalcemia and hyperphosphatemia

AEs of oral containing phosphate binders

Hypercalcemia and

Constipation

Iron based phosphate binders

Ferric citrate and Sucroferric oxyhydroxide