Renal System Flashcards
Causes of Acute Tubular Necrosis
Causes leading to ischemic damage or toxin exposure: IV consrast, Myoglobin 2/2 crush injury, Aminoglycosides, Lead, Cisplatin, Hemoglobinuria
Cast seen with Acute Tubular Necrosis
Muddy brown cast
PPX for ATN 2/2 IV contrast
Vigorous hydration and N-acetyl-cysteine
Major Causes of AIN
Causes leading to pseudo-allergic rxn:
1) Drugs (TMP-SMX, PCNS, Cephalosporins, Rifampin)
2) Infections (Pyelonephritis)
3) Deposition Disease (Sarcoid, Amyloid)
Cast seen with AIN
White cell casts + eosinophils
Causes of papillary necrosis
1) S - Sickle Cell trait/Disease
2) A - Acute pyelonephritis
3) A - Analgesics (NSAIDs)
4) D - Diabetes
Common causes of respiratory acidosis
COPD, asthma, drugs (e.g. opioids, benzodiazepines, barbiturates, alcohol), chest wall problems (paralysis, pain), sleep apnea
Common causes of metabolic acidosis
Ethanol, diabetic ketoacidosis, uremia, lactic acidosis (e.g. sepsis, shock, bowel ischemia), methanol/ethylene glycol, aspirin/salicylate overdose, diarrhea and carbonic anhydrase inhibitors
Common causes of respiratory alkalosis
Anxiety/Hyperventilation and aspirin/salicylate overdose
Common causes of metabolic alkalosis
Diuretics (except CA inhibitors), vomiting, volume contraction, antacid abuse/milk-alkali syndrome, hyperaldosteronism
Presentation of aspirin overdose
Tinnitus, hypoglycemia, vomiting, h/o swallowing pills, metabolic acidosis + respiratory alkalosis
Tx: Alkalinization of urine with bicarbonate
Blood gas of a patient with asthma that changes from alkalotic to normal means..
Pt is about to CRASH b/c lungs are getting tired and are starting to retain more CO2! INTUBATE!
Signs and symptoms of hyponatremia
Lethargy Seizures MS change or confusion Cramps Anorexia Coma
First step to determine cause of hyponatremia?
Look at volume status
Causes of hypovolemic hyponatremia
dehydration, diuretics, diabetes, Addison disease/hypo-aldosteronism (high K+)
Causes of euvolemic hyponatremia
SIADH, psychogenic polydipsia, oxytocin use
Causes of hypervolemic hyponatremia
Heart failure, nephrotic syndrome, cirrhosis, toxemia, renal failure
How to treat hypovolemic hyponatremia
Normal Saline
How to treat euvolemic or hypervolemic hyponatremia
Water/fluid restriction
Patient who presents with polyuria and polydipsia, what’s your differential?
Diabetes mellitus
Diuretics use
Diabetes insipidus
Primary polydipsia (psych, water deprevation helps urine osmolarity increase appropriately)
Medication used to treat SIADH if water restriction fails?
Demeclocycline (induced nephrogenic DI)
Central pontine myelinolysis
2/2 to quick correction of Sodium:
- High to low brain blows
- Low to high pons die
Effect of serum glucose on sodium levels?
Once glucose gets above 200, it causes sodium to DECREASE (falsely) by 1.6 mEq/L for each rise of 100 mg/dL in glucose
Adrenal insufficiency presents with:
Hyponatremia
Low BP
Elevated potassium
What causes hyponatremia in pregnant patient about to deliver?
Oxytocin
Most common cause of hypernatremia?
Dehydration caused by inadequate fluid intake relative to body needs
How is hypernatremia treated?
Water replacement with Normal saline until pt is hemodynamically stable, then he can be switched to 1/2 normal saline. NEVER ADD D5 for hypernatremia.
Signs and symptoms of hypokalemia?
Muscular weakness (paralysis and ventilatory failure) ECG changes: loss T wave or T-wave flattening, the presence of U waves, PVAC and VTach or ATach
Effects of potassium on digoxin.
Potassium levels should be monitored in all patients taking digoxin, especially if they are also taking diuretics. The heart is particularly sensitive to hypokalemia in patients with digoxin.
What electrolyte to you check is hypokalemia persists even after oral replacement?
Check magnesium
Signs and symptoms of hyperkalemia
Weakness and paralysis
ECG changes: tall peaked T waves –> widening QRS, prolongation of PR interval –> loss of P waves –> sine wave pattern
Causes of hyperkalemia
Renal failure
Severe tissue destruction (since K+ is intracellular)
Hypoaldosteronism
Medications (Spironolactone, beta blockers, NSAIDs, ACE inhibitors, ARBS)
Adrenal insufficiency
Hyperkalemic asymptomatic patient…r/o
Hemolyzed blood, so repeat the test!
Treatment of Hyperkalemia:
1) First, if cardio-toxicity –> calcium gluconate (cardioprotective, although it does NOT change K+ levels)
2) Sodium bicarbonate (alkalosis causes potassium to shift into cells)
3) Glucose with insulin (insulin forces K+ into cells, glucose prevents hypoglycemia)
4) Beta2-agonists also work if none of the above are available
4) Dialysis if refractory to above management
What is the first thing to correct for with hypocalcemia?
Recall that calcium exists in a free or bound form. So, first check albumin level and/or ioniced or free Ca2+ level to make sure TRUE hypocalcemia is present.
Correction: every 1g/dL decrease in albumin, add 0.8 mg/dL to calcium value
Pseudohypoparathyroidism
Shift fingers, short stature, mental retardation, normal levels of parathyroid hormone with end -organ unresponsiveness to parathyroid hormone
Relationship between calcium and phosphorus
Phosphorus and calcium levels usually go in opposite direction. In chronic renal failure, efforts are to increase calcium while reducing phosphorus.
Outpatient cause of hypercalcemia?
Hyperparathyroidism
Inpatient cause of hypercalcemia?
Malignancy
Marker for Familial hypocalciuric hypercalcemia
Low urinary calcium despite hypercalcemia
Treatment of hypercalcemia?
IV fluids, Furosemide
Who typically gets hypomagnesemia?
Alcoholics
Side effects of hypermagnesemia?
Decreased deep tendon reflexes
Hypotension
Respiratory failure
What is the maintenance fluids of choice for patients who are not eating?
1/2 Normal saline with 5% dextrose in adults (consider adding potassium chloride)
