Electrolytes Part 3 (Magnesium, Ca 2+ and Phosphate)-Paulson Flashcards
Hypermagnesemia:
-plasma Mg=
> 2.5 mEg/L
Hypermagnesemia:
-how common?
Relatively rare other than in the setting of renal impairment
Hypermagnesemia:
pathophysiology?
- Oral ingestion: Laxative abusers, accidental overdose of Epsom salts
- Magnesium enemas
-Magnesium infusion:
Used for women with preeclampsia or eclampsia
- Renal insufficiency:
- -Magnesium is excreted renally–> levels rise as CKD worsens
- -Antacids or laxatives in regular doses can provoke severe ↑ Mg
Hypermagnesemia:
-clinical features?
- May be asymptomatic, esp. if level <4
- Neuromuscular toxicity is most frequently observed
- 4-6: nausea, flushing, headache, lethargy, drowsiness, ↓DTRs
- 6-10: somnolence, hypocalcemia, absent DTRs, hypotension, bradycardia, EKG changes
- > 10: Muscle paralysis–> flaccid quadriplegia, apnea, respiratory failure, complete heart block, cardiac arrest
Hypermagnesemia:
-Diagnostic labs?
- Magnesium level
- BMP
- EKG
Hypermagnesemia:
-EKG findings?
- Diminished conduction
- Widened QRS
- Prolonged PQ interval
Hypermagnesemia:
tx?
- Normal renal function:
- -Stop the offending agent
- -May add diuretic to ↑ renal excretion of magnesium
- Calcium gluconate given IV–>Helps stabilize cardiac membrane
- Hemodialysis if severe + renal impairment
Hypomagnesemia=
Plasma magnesium levels < 1.8 mEq/L
Hypomagnesemia:
Most common causes?
- **Chronic diuretic therapy (loop and thiazide)
- Chronic alcoholism
- **Chronic diarrhea
- Hypoparathyroidism
- Nutritional deficiencies (prolonged TPN, malnutrition)
- Uncontrolled diabetes mellitus
- **Chronic PPI usage
Hypomagnesemia:
-neurological features?
- Tetany-may have a positive Trousseau and Chvostek sign, muscle spasm, muscle cramps
- Seizures
- Involuntary movements
Hypomagnesemia:
-Cardiovascular-EKG findings?
- Widening of QRS & peaked T waves (moderate)
- Prolonged PR interval, QRS widening, and diminished T wave (more severe)
- Frequent PACs and PVCs, may develop sustained afib
- Ventricular arrhythmias –> death
Hypomagnesemia:
-diagnostic labs?
- These patients often have a concurrent **hypokalemia & hypocalcemia
- If cause can’t be determined from HPI, 24 hour urine magnesium excretion or fraction excretion of magnesium on a random urine can help differentiate between GI and renal losses
Hypomagnesemia:
-tx of severe Sx?
Severe Sx ie tetany, arrhythmias, or seizures–>
- IV magnesium sulfate
- With continuous cardiac monitoring
- Reduce dose in those with CrCl <30
Hypomagnesemia:
tx of Asymptomatic or minimal symptoms?
Oral replacement:
- Magnesium chloride or magnesium oxide
- **Diarrhea is a major side effect
- Correct underlying disease if possible
Hypercalcemia=
Serum Calcium > 10.5 mEq/L
Normal serum Calcium=
9 to 10.5 mg/dL
Mild hypercalcemia=
10.5 to 12 mg/dL
Hypercalcemia:
-what serum Ca 2+ can be life threatening?
> 14 mg/dL
Hypercalcemia: CAUSES
-malignancy?
- Ectopic secretion of PTH by tumor
- Multiple myeloma
- Bone mets
Hypercalcemia: CAUSES
-endocrine?
- **Hyperparathyroidism
- MEN (multiple endocrine neoplasias)
- Hyperthyroidism
- Pheochromocytoma
- Adrenal insufficiency
Hypercalcemia: CAUSES
-ex’s of granulomatous diseases
Sarcoidosis TB Histoplasmosis Berylliosis Coccidiomycosis
Hypercalcemia: CAUSES
-drugs?
- Vitamins A and D
- **Thiazide diuretics
- Estrogens
- Milk-alkali syndrome
- Lithium
Hypercalcemia: CAUSES
-miscellaneous?
- Dehydration
- Prolonged immobilization
- Iatrogenic
- Rhabdomyolysis
- Familial
- Lab error
Hypercalcemia: CAUSES
-which 2 causes are the MOST important to remember?
-MALIGNANCY -HYPERPARATHYROIDISM
Hypercalcemia: presentation
Sx?
- Symptoms: often vague and nonspecific
- Non-focal abdominal pain
- Constipation
- Fatigue
- Diffuse body aches
- Anorexia
- Nausea/Vomiting
- Signs of intravascular volume depletion (tachycardia, orthostatic hypotension)
- Anxiety, depression, confusion, hallucinations
Hypercalcemia: presentation
severe?
- Lethargy, altered mental status, seizures, coma
- Cardiac conduction abnormalities
Ex’s of cardiac conduction abnormalities associated with hypercalcemia
Bradyarrhythmias Sinus arrest AV blocks AF VT LBBB or RBBB
Hypercalcemia:
-other possible EKG findings?
- ST segment elevation
- Short QT interval – “classic” finding but not reliably seen in most patients (KNOW shortened QT interval)
Hypercalcemia: presentation
-rhyme to help remember the Sx?
Painful BONES Renal STONES Abdominal GROANS Psychic MOANS (or psychiatric overtones)
Hypercalcemia: diagnostic labs?
-ionized Ca vs total Ca:
-The serum total calcium represents both bound and unbound calcium
- Can measure IONIZED CALCIUM as a separate lab test, or can estimate:
- -Account for albumin levels (next slide)
- -May also check a 24 hour urine collection
slide 27
?
Pts with hypercalcemia might have a “normal” calcium level if their ______ is low and vice versa
albumin
- **Need to correct for albumin levels
- **Or measure ionized calcium levels
Corrected calcium =
measured total calcium + [0.8 x (4-albumin)]
hypercalcemia:
-Additional Labs?
After confirming hypercalcemia:
-Serum PTH
If high–> Likely primary hyperparathyroidism
If low –> Check vit D level & PTHrP
Hypercalcemia: tx?
- Patients in hypercalcemic crisis are usually dehydrated
- IV access and cardiac monitoring
- Infuse NS “wide open” until BP and perfusion normalize
For treatment of hypercalcemia, the routine use of __________ is no longer recommended
furosemide
–>Furosemide can actually worsen hypercalcemia if given to patients who are not yet volume replete; can adversely affect hemodynamics and renal status
Hypercalcemia tx:
- Other tx methods?
- what is the last resort tx method for severe hypercalcemia?
- *Osteoclast-inhibiting therapies:
- Bisphosphonates (often used in hypercalcemia of malignancy)
- Calcitonin
- Glucocorticoids
-If severe, may need dialysis (last resort)
Hypercalcemic crisis resulting from primary hyperparathyroidism: treatment?
*urgent parathyroidectomy is potentially curative
EKG findings:
-Hypercalcemia
shortened QT
EKG findings:
-hypocalcemia?
prolonged QT
Hypocalcemia:
-defined as serum calcium of ____ or ionized calcium of _______
Serum calcium (corrected) <8.5 mg/dL or ionized calcium of <4.6 mg/dL
Hypocalcemia: pathophysiology
-Hypoparathyroidism?
- Genetic disorder
- Postsurgical or Radiation-induced damage
- Hungry bone syndrome
- Infiltration of the parathyroid gland (ie: mets)
- Autoimmune destruction
Hypocalcemia: pathophysiology
-drugs?
- Bisphosphonates & meds used to treat hypercalcemia
- Calcium chelators (EDTA, citrate, phosphate)
- Phenytoin
- Fluoride poisoning
Hypocalcemia: pathophysiology
-other causes?
- **Hypomagnesemia
- Vitamin D deficiency
- PTH resistance
- Renal disease
- Loss of calcium from circulation
Hypocalcemia: pathophysiology
-describe the etiology of loss of calcium from circulation
- Tumor lysis
- Acute pancreatitis
- Osteoblastic metastases
- Sepsis or acute severe illness
Hypocalcemia: classic clinical features (KNOW! hint: 2 signs)
- Trosseau sign
- Chvostek sign
Trosseau sign=
carpal tunnel spasm after BP cuff is applied for 3 minutes
Chvostek sign=
Spasm of facial muscle after tapping facial nerve in front of ear
Hypocalcemia: clinical features (list ex’s)
- May be asymptomatic
- Muscle spasm or muscle cramps
- Tetany
- Paresthesias (perioral and peripheral)
- Confusion
- Seizures
- Dry skin, brittle nails, coarse hair
- Carpopedal spasm or tetany
- Anxiety, depression, dementia
- Laryngospasm or bronchospasm
- EKG: Prolonged QT or ST flattening
Hypocalcemia: diagnostic labs?
- Total serum calcium (corrected for albumin) or ionized calcium
- Serum phosphate
- Vitamin D level
- Serum PTH
- Magnesium level
- BMP
- EKG
Hypocalcemia: tx
-acute OR severely symptomatic?
IV calcium gluconate
–>Treat any emergent cardiovascular issues
Hypocalcemia: tx
-mild?
- **can be treated outpatient with oral calcium + vit D (calcitriol preferred)
- **Treat any concurrent hypomagnesemia 1st to effectively treat the hypocalcemia
Hyperphosphatemia:
-defined as serum phosphate of _____
> 4.5 mg/dL
Hyperphosphatemia:
Pathophysiology- Acute causes (list 6)
- **Acute renal failure (ARF)
- Rhabdomyolysis
- **Tumor lysis syndrome
- Acute phosphate load
- Hypoparathyroidism (acquired)
- Extracellular shift of phosphate
Describe acute phosphate load
=Excess phosphate in TPN, rapid administration of phosphate-rich drugs (ie: fosphenytoin), phosphate-containing laxatives given in prep for colonoscopy, vitamin D toxicity
Describe the MC causes of hypoparathyroidism (acquired)
-**Parathyroidectomy, infiltration of parathyroid glands, metal overload (ie: hemochromatosis, Wilson disease, thalassemia)
Describe the MC causes of extracellular shift of phosphate
Lactic acidosis, ketoacidosis, respiratory acidosis, crush injuries
Hyperphosphatemia:
-list Ex’s of chronic causes
- CKD **
- Hypoparathyroidism (congenital or hereditary)–> Autoimmune, gene mutations
- Pseudohypoparathyroidism
Hyperphosphatemia:
clinical Sx?
-acute severe hyperphosphatemia can lead to accompanying ________
-*Most asymptomatic
- Acute, severe hyperphosphatemia can lead to accompanying hypocalcemia:
- -Tetany, muscle cramps, perioral numbness or tingling, seizures
- -Trousseau or Chvostek sign, hyperreflexia, carpopedal spasm, seizure
Hyperphosphatemia:
-other Sx?
-May have s/s of uremia:
Fatigue, n/v, AMS, pruritis, SOB, sleep disturbances
-May have painful masses around joints, skin ulcerations, irritated conjunctiva–> Ectopic calcifications
Hyperphosphatemia:
-diagnostic labs?
- Serum phosphorous
- PTH to see if this is the cause
- Serum calcium
- Vit D level to look for toxicity
- ?Renal ultrasound
Hyperphosphatemia: tx?
**Treat underlying Cause
Tx of Acute hyperphosphatemia and normal renal function
Saline + diuresis (loop diuretic) forces phosphaturia
Tx of Acute hyperphosphatemia 2/2 to hypoparathyroidism
Calcium + Vit D supplementation to correct hypocalcemia
Tx of Acute hyperphosphatemia 2/2 AKI
- **Phosphate binders when level is > 6:
- -If serum ionized calcium low: use a calcium based binder: calcium carbonate or calcium acetate
- -If serum ionized calcium high, use a non-calcium-based binder: sevelamer, aluminum hydroxide, lanthanum carbonate
-** Dialysis if severe (serum phosphate > 12) or symptomatic
Tx of Acute hyperphosphatemia 2/2 CKD
-Start tx when levels above normal range
- Restrict dietary phosphate to 800-1000 mg
- ->Dark colas, oysters, cheese, milk, organ meats, ice cream, chocolate, nuts/seeds
- Phosphate binders to ↓ intestinal phosphate absorption
- Dialysis to remove excess phosphate
Hypophosphatemia is defined as a serum phosphate of _____
Serum phosphate < 2.5 mg/dL
Hypophosphatemia: pathophysiology?
- Respiratory alkalosis (causes a rapid redistribution of phosphate from serum into intracellular space)
- Sepsis
- Refeeding syndrome
- Alcohol withdrawal
- Renal transplantation
- Hypercalcemia of malignancy
- Hyperparathyroidism
- Hereditary rickets
- Vitamin D deficiency
- Inhibition of phosphate absorption (antacids, phosphate binders, niacin)
- Inadequate intake
Hypophosphatemia: clinical Sx?
- Rarely symptomatic unless serum phosphorous is <1 mg/dL
- Metabolic encephalopathy
- Proximal myopathy
- Impaired myocardial contractility
- Respiratory failure
- Dysphagia
- Rhabdomyolysis
- Hemolysis
Hypophosphatemia: diagnostic labs?
-Serum phosphorous
- Urinary phosphorous excretion (24 hour or random specimen + calculate fractional excretion of filtered phosphate)
- -Excreting < 100 mg or FEPO4 <5% –> low renal phosphate excretion
–Excreting >100 mg or FEPO4 >5% shows renal phosphate wasting
What is the likely cause of hypophosphatemia when the Pt is excreting < 100 mg or FEPO4 <5% (low renal phosphate excretion) ?
Likely cause is internal redistribution or ↓ intestinal absorption
What is the likely cause of hypophosphatemia when the Pt is excreting >100 mg or FEPO4 >5% (shows renal phosphate wasting) ?
Likely cause: hyperparathyroidism, vit D deficiency, renal tubular defect
Hypophosphatemia: Asymptomatic + serum phosphate <2.0 mg/dL
-Tx?
**Oral phosphate therapy
Hypophosphatemia:
symptomatic
-tx?
- ** 1.0-1.9: Oral phosphate (but IV if rhabdo, CNS sx present, or hemolysis)
- ** <1.0: IV phosphate, then switch to PO once serum phosphate is >1.5
Hypophosphatemia:
urinary phosphate wasting
-tx?
- More difficult to treat
- Dipyridamole QID helps to ↑ phosphate levels
- -Increases renal phosphate reabsorption
