Electrolyte Imbalances Flashcards
A patient has carpal spasm when a blood pressure cuff is inflated. Which diagnostic testing will the primary care provider consider to evaluate the cause of this finding?
Calcitriol level
Magnesium and vitamin D
Protein electrophoresis
C-reactive protein
Correct! The Trousseau’s sign indicates neuromuscular irritability, which occurs with hypocalcemia. Because hypomagnesemia and vitamin D deficiency may cause hypocalcemia, these should be evaluated to help determine a cause.
Which test should be performed initially to assist with the differential diagnosis of a patient who has a serum potassium level of 3 mEq/L and a normal blood pressure?
Plasma aldosterone
Serum bicarbonate
Plasma renin activity
Serum magnesium
Correct! In patients with hypokalemia with normal blood pressure, serum bicarbonate should be assessed to evaluate for diabetic ketoacidosis, metabolic acidosis, or renal tubular acidosis. If bicarbonate is normal, serum magnesium may be assessed.
Hypercalcemia
Ionized calcium >5.3 or corrected calcium > 10.5
Hypocalcemia
Ionized calcium <4.4
Corrected calcium <8.5
Hypercalcemia causes
Primary hyperparathyroidism, excess secretion of PTH
Renal failure, metabolic alkalosis, vitamin D excess
Hypercalcemia Presentation
Neuromuscular, cardiac, GI depression
Short QT interval, heart blocks
Constipation, N/V
Hypocalcemia Presentation
Muscle weakness, tetany, convulsions
Seizures, cataracts, hyper-reflexia (Chvostek / Trousseau signs)
Parkinson like tremors
Hypotension, bradycardia
Chronic = coarse hair, brittle nails, scaly skin
Chronic Hypocalcemia
Significant Vitamin D deficiency is usually the cause
‘Hungry bone syndrome’
Hypoparathyroid
Calcium disturbance Referral
Any symptomatic calcium disturbances need ED refer
For severe hypocalcemia treat with calcium gluconate immediatley
Hypocalcemia Treatment
Vitamin D therapy for chronic hypocalcemia
Calcium supplements as needed
Hypercalcemia treatment
For mild - hydration and avoidance of things that worsen it
Severe = ICU admit, aggressive fluids to prompt urine dilution
May require dialysis
Hypokalemia Presentation
Clinical signs and symptoms of acute hypokalemia include: weakness, palpitations, nausea, vomiting, hypotension, metabolic alkalosis, potassium less than 2.5, and EKG changes. EKG changes in hypokalemia include flattened T waves, the presence of U waves, ST depressions, and ventricular arrhythmias
Normal Potassium Range
3.5 - 5
Causes of Potassium Disturbances
Both hyper- and hypokalemia can result from potassium redistribution within the body’s cells. Hyperkalemia can also result from impaired renal excretion or increased intake. Hypokalemia can result from increased potassium losses (renal or extrarenal) or from decreased potassium intake. Pseudo hyper- and hypokalemia are not uncommon and must always be ruled out.
Hyperkalemia Presentation
chiefly cardiac and are best monitored by EKG.
Progressive EKG changes seen in hyperkalemia are peaked T waves, PR prolongation, intraventricular block, sine waves, and ultimately ventricular fibrillation and asystole.
Severe hyperkalemia can cause muscle weakness and rarely ascending paralysis as seen in hypokalemia
Hypokalemia Causes
- Cellular redistribution
- Extrarenal loss
- renal loss
- decreased intake
- Pseudo-hypokalemia (hemolysis of sample)
Hyperkalemia Causes
- Cellular redistribution
- Decreased renal excretion
- excess intake
- Pseudo hyperkalemia (bad lab sample)
Medications that cause redistribution
Insulin, Beta agonists, decongestants, verapamil, xanthines, laxative, diretics = hypokalemia
ACE-I, ARBs, NSAIDs, K sparing diuretics, heparin, lithium, beta-blockers, anectine = hyperkalemia
Potassium and Diuretics
When diuretics are prescribed, the patient’s serum potassium concentration should be checked before initiation of treatment and then at week 1 and week 4 after the initiation of therapy. In patients with chronic hyperkalemia, any use of ACE inhibitors, ARBs, NSAIDs, potassium sparing diuretics, or salt substitutes containing potassium chloride should be reassessed and likely discontinued
Hypokalemia Treatment
Oral or IV potassium - 20 moL/hour is standard for IV in severe cases. Oral is usually better for chronic
Hyperkalemia Treatment
Symptomatic - ED refer, IV Calcium to stabilize heart cells, lower serum potassium with beta agonists, Insulin/glucose combinations
Chronic - Often occurs in diabetics, kidney patients, heart failure. Discontinue mediations that contribute
Sodium Disturbances
Hyponatremia = NA+ < 120 Hypernatremia = NA+ > 145
Causes of Hypernatremia
GI Distress, diuresis, water loss, impaired ability to express thirst, no access to water
Diabetes insipidus can cause it as water intake cannot compensate for fluid loss
Hypernatremia presentation
major clinical feature of hypernatremia is a central nervous system disturbance that results from dehydration and shrinkage of brain cells.
Agitation, irritability, tremor, spasticity, hyper-reflexia occur at very high levels
Recent history of water loss is significant
Types of Hypernatremia
Hypervolemic = excess sodium with low water intake Hypovolemic = Free water deficit / diarrhea, diuresis, febrile Euvolemic = central diabetes insipidus,
Hypernatremia Treatment
> 155 = ED refer
Fluid resuscitation if hypovolemic hypernatremia
Lowering sodium level must be done slowly (50% fluid correction in 24 hours, rest in 48-72 hours)
Euvolemic Hypernatremia needs desmopressin
Hypervolemic hypernatremia may ned diuretics and hypotonic fluids
Hyponatremia Types
Acute = fluid overload, usually in hospitals Chronic = diuretic therapy Exercise-associated = increased water intake before/during/after intense exercise
Hyponatremia presentation
new-onset confusion, severe headache, seizures, or coma. More subtle signs and symptoms associated with hyponatremia include headache, blurred vision, dizziness, lethargy, weakness, irritability, restlessness, impaired central nervous system function, history of falls, nonspecific gastrointestinal complaints (e.g., anorexia, nausea, vomiting), influenza-like symptoms, cardiac or respiratory distress, dysgeusia, unusual water-drinking behavior, or weight changes.
Syndrome of Inappropriate Antidiuretic Hormone
Excess antidiuretic hormone causes the body to retain too much water and leads to low sodium and low serum osmality
Causes of Hyponatemia
Many cases are medication related. Best practice to obtain serum values after stating a medication known to cause sodium changes
-carbamazepine, clofibrate, levetiracetam, NSAID, thiazides, SSRIs
Exercise associated disturbances Education
Fluid consumption based on thirst
Sodium supplements are not effective for most
Atheletes need evaluation for sodium disturbances
