Sodium (Na+)*

Hydrogen (H+)

Potassium (K+)*

Calcium (Ca2+)

Magnesium (Mg+)

Combines with H+ in gastric mucosa to form HCL

Diffuses between ECF and ICF to regulate osmotic pressure differences between compartments

Assists in nerve impulse transmission

Chlorides Major homeostatic regulators

N/V***

NG suction

CHF excessive sweating

Severe diarrhea***

Adrenal insufficiency

Hyperaldosteronism

Hyponatremia

Renal failure

Agitation

Muscle cramps

Increased DTR

Shallow respirations

Arrhythmias

Dehydration

Cushing's syndrome

Hyperventilation

Cardiac decomposition

Renal failure

Often not associated with symptoms

Dehydration if associated with N/V

Weakness

Intense thirst

Hypo/Hyperchloremia

Treatment

Treat the underlying cause

-Volume overload or dehydration: Goal is euvolemia

-Endocrine abnormalities: Refer to endocrinologist

-Renal abnormalities: Refer to nephrologist

Builds strong bones/teeth

Essential for blood coagulation

Decreases neuromuscular irritability

Promotes normal nerve transmission

Needed for muscle contraction

Parathyroid hormone raises Ca++ levels by increasing osteoclast activity

Calcitonin lowers Ca++ levels by inhibiting osteoclast activity

Phosphorous has an inverse relationship with Ca++

Vitamin D is necessary for Ca++ absorption and utilization 

Hypoalbuminemia (pseudohypocalcemia)

Alkalosis

Excessive IVF use

Hypoparathyroidism (rare)

Hyperphosphatemia

Osteomalacia

Diarrhea

Ricketts

Malabsorption

Abdominal pain

Cramping

Perioral and peripheral paresthesias

Larynngospasm and stridor

Tetany

Trousseau's sign

QT prologation

Hypocalcemia treatment

Asymptomatic

Treat low Mg+ if present

Oral calcium

-Tums 500

-Oscal (calcium carbonate)

Oral Vit D

-Rocaltrol

Hypocalcemia Treatment

Symptomatic, severe

IV calcium gluconate

D5W (1L) w/ 6-8 10cc vials of calcium gluconate (558-744 mg Ca++) infused at a rate to keep serum Ca++ levels 7-8.5 mgdl

Frequent Q4-6H blood ca++ monitoring

Increased intake

Primary hyperparathyroidism

Hypophosphatemia

PTH secreting tumors

Adrenal insufficiency

2 or 3 degree hyperparathyroidism

Multiple myeloma

Prolonged immobilization

Mild hypercalcemia tends to be asymptomatic

N/V

Peptic ulcer disease

Renal colic

Anorexia

Constipation

Polyuria

Hypercalcemia treatment

Normal renal function

IV 0.45 NS or 0.9 NS rapid infusion to force calciuresis

Bisphosphonates (take 48-72 hours)

Look for malignancy if H&P does not shed light on the cause

Activates many enzymes 

Necessary for utilization of K+, Ca++, and protein

Promotes regulation of serum Ca++, K+ and phosphorus

Essential for neuromuscular and heart function

Chronic diarrhea

Hepatic cirrhosis

Hyperthyroidism

Hypoparathyroidism

Chronic alcoholism

Malabsorption syndromes

Diuretic use

Ulcerative colitis

Hypomagnesemia treatment

Mild asymptomatic

Oral Mg++ repletion

Monitor levels periodically

Hypomagnesemia Treatment

Symptomatic

IV MgSo₄

Monitor DTRs for hyporeflexia of hypermagnesemia

Renal failure

Hypothyroidism

Adrenalectomy

Addison's disease

Dehydration

Use of thiazides, ethacrynic acid

Magnesium containing antacids

Diminished DTRs

Nausea

Lethargy

Drowsiness

Flushing

Headaches

Hypotension

Bradycardia

EKG changes

Discontinue exogenous sources

Calcium antagonizes Mg++ and can be given IV

Avoid magnesium containing compounds in pts with renal failure

Regulates fluid volume within ECF

Maintains blood volume and controls size of vascular space

Acts as a buffer (NaHCO₃) regulating H+ concentration

Stimulates nerve impulse conduction

Controls body H2O distribution between ECF and ICF

Aldosterone controls secretion and rentention

Atrial natriuretic peptide stimulates excretion

Severe burns

Severe diarrhea

Vomiting

Excessive hypotonic IV fluids

Excessive sweating

Addison's disease

Syndrome of inappropriate antidiuretic hormone secretion 

Severe nephritis

CHF

Diuretics

Symptoms are dependent on severity

Nausea

Malaise

Headache, lethargy, and disorientation

Respiraotry arrest

Seizures and coma

Brainstem herniation

Death

Hyponatremia Serum osmolality

Normal

280-295 mosm/kg

Isotonic hyponatremia

Hyperproteinemia

Hyperlipidemia

-Chylomicrons

-Triglycerides

-Cholesterol (rare)

Hyponatremia serum osmolality

High

> 295 mosm/kg

Hypertonic hyponatremia

Hyperglycemia

Radiocontrast agents

Mannitol, sorbitol, glycerol, maltose

Hyponatremia serum osmolality

Low

< 280 mosm/kg

Hyponatremia Assessment of volume status

Hypovolemia

Total body water ↓

Total body Na+ ↓↓

U(Na_) >20 mEq/L

U(Na+) <20 mEq/L

Hyponatremia Assessment of volume status

Euvolemia 

(no edema)

Total body water ↑

Total body Na++  ↔

U(Na+) >20 mEq/L

Hyponatremia Assessment of volume status

Hypervolemia

Total body water ↑↑

Total body Na+ ↑

U(Na+) >20 mEq/L

U(Na+) < 20 mEq/L

Hyponatremia Hypovolemia

Renal Losses

Diuretic excess

Mineralocorticoid deficiency

Salt-losing deficiency

Bicarbonaturia with renal tubal acidosis and metabolic alkalosis

Ketonuria

Osmotic diuresis

Hyponatremia Hypovolemia

Extrarenal  losses

Vomiting

Diarrhea

Third spacing of fluids

Burns

Pancreatitis

Trauma

Glucocorticoid deficiency

Hypothyroidism

Syndrome of inappropriate ADH secretion

Drug-induced

Stress

Nephrotic syndrome

Cirrhosis

Cardiac failure

Hyponatremia Treatment

Mild to moderate 

Restrict free water

If hypovolemic, replete IVV with isotonic fluids

Hypervolemic patient require diuretics

Hyponatremia Treatment

Severe

Hospitalization

Daily weights

Frequent lab monitoring

Hypertonic saline (3%) - limit Na+ rise to 8-12 mEq/L per day

Demeclocycline P.O. inhibits ADH effects on the kidney causing free H2O

Dehydration and insufficient water intake

Conn's syndrome

Primary aldosteronism

Coma

Diabetes insipidus

Orthostatic hypotension

Oliguria

Lethargy

Irritability

Hyperthermia

Delirium

Seizures

Coma

Hypernatremia

Urine osmolality

>400 msom/kg

Hypernatremia

Urine osmolality

<250 msom/kg

Hypernatremia

urine osmolality

>400 msom/kg

Nonrenal losses

Renal water conserving ability is functioning

If water intake falls behind hypotonic fluid loss (sweating, respiratory tract, gut)

Hypernatremia

urine osmolality

>400 msom/kg

Renal Losses

Hypernatremia

Urine Osmolality

< 250 msom/kg

Hypernatremia with dilute urine is a characteristic of diabetes insipidus

Nephrogenic DI

Central DI

DDAVP challenge to distinguish these 2 conditions

Measure urine osmolality

Administer DDVAP (0.03 μg/kg SC or IV) and repeat measurement of urine osmolarity 1-2 hours later.

An increase >50% indicates severe central DI. A smaller or absent response is strongly suggestive of nephrogenic DI.

This needs to be done in the hospital for close monitoring and observation

Hypernatremia Treatment

Hypernatremia w/hypovolemia

Isotonic saline to restore euvolemia

After adequate restoration of IVV, hypotonic fluids can be used to complete the remaining volume

Hypernatremia Treatment

Hypernatremia w/euvolemia

Water ingestion 

IV D5W

Diuretic use in the  presence or renal insufficiency may increase total volume requirements (↓ concentration ability)

Hypernatremia Treatment

Hypernatremia w/hypervolemia 

Hypotonic D5W

Loop diuretics

Dialysis

Regulates water and e-content of ICF

Helps promote nerve impulse transmission

Assists in tranforming carbs into energy and restructuring amino acids and proteins

Assists in acid/base balance by cellular exchange with H+

Diarrhea

Starvation

Renal tubular acidosis

Diuretics

Malabsorption

Severe burns

Liver disease with ascites

Excessive licorice ingestion

Hypomagnesemia

Muscle weakness

Fatigue

Muscle cramps

Constipation/ileus

Flaccid paralysis

Hyporeflexia

Hypercapnia

Tetany

Rhabdomyolysis

Impaired diuresis

Impaired myocardial performance

Increased risk of arrhythmia

Increased risk for mortality from sudden death and progressive cardiac failure

Hypokalemia 

Renal or extrarenal losses?

Urinary K+ < 20 mEq/L

Diarrhea 

Vomitting

Urinary K+ >40 mWq/L

Mineralocorticoid excess

Bartter syndrome 

Liddle syndrome

Treatment of Hypokalemia

Guidelines for IV potassium replacement

I.V. administration:

» 5-10 mEq/hr can be done without cardiac monitoring in a stable patient. Follow-up serum K+.

» 20 mEq/hr requires cardiac monitoring & careful monitoring of serum K+. When plasma K+ >2.5 mEq/L, reduce infusion to 10 mEq/hr.

» IV KCl <30-40 mEq/L in peripheral vein.

»Max K+ concentration 40 mEq/L in peripheral

vein and 60 mEq/L in a central vein.

» IV: KCl or KPhos

Change to P.O. Rx when feasible. High K+ foods.

Renal failure-acute or chronic

Cell damage (burns, etc.)

Acidosis

Addison's disease

Hemorrhage

Drugs that inhibit K+ secretion

Insulin deficiency

Muscle weakness

Flaccid paralysis

Ileus

Bradycardia

Arrhythmia

ventricualr fibrillation

Cardiac arrest

Inhibitors of the renin-angiotensin-aldosterone axis and K+ sparing diuretics should be used cautiously in patients with renal disease or liver/heart failure

ACE inhibitors

ARBs

Spironolactone

Eplernone (Inspra)

Triamterene

(dyrenium)

Rule out spurious hyperkalemia

Fist clenching

Cell lysis

Lab draw IV K+

Review meds and DC contributors

Decrease dietary K+ intake

Cardiac toxicity

Muscle paralysis

K+ >6.5 mEq/L

Remember ACE

Antagonism

Cellular redistribution

Excretion

Calcium antagonizes the arrhythmias of hyperkalemia

IV calcium chloride or calcium gluconate: 10%, or 10 ml IV over 2-3 min. Can repeat in 5-10 mins