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USMLE Step 2 CK-Renal
How does hypernatremia present? - correct answer thirst oliguria or polyuria mental status changes weakness focal neurologic deficits seizures "doughy" skin and signs of volume depletion What are the causes of hypernatremia? - correct answer 6Ds
- diuresis
- dehydration
- diabetes inspidus
- docs (iatrogenic)
- diarrhea
- disease (kidney, sickle cell) How is hypernatremia tx? - correct answer Treat underlying causes and replace free-water deficit w/ hypotonic saline, D5W, or oral water, depending on volume status
- correction of chronic hypernatremia (>36-48hrs) should be accomplished gradually over 48-72hrs (=0.5 mEq/hr) to prevent neurologic damage secondary to cerebral edema How does hyponatremia present? - correct answer may be Asx or may present w/ confusion, lethargy, muscle cramps, hyporeflexia, and nausea Can progress to seizures, coma, or brain stem herniation What are the causes of hypervolemic hyponatremia? - correct answer nephrosis
cirrhosis cardiosis What are the causes of hypervolemic hypotonic hyponatremia? - correct answer renal failure nephrotic syndrome cirrhosis CHF hypothyroidism secondary/tertiary adrenal insufficiency What are the causes of euvolemic hypotonic hyponatremia? - correct answer SIADH renal failure drugs psychogenic polydipsia oxytocin use What are the causes of hypovolemic hypotonic hyponatremia? - correct answer diuretics (esp thiazides) vomiting diarrhea bleeding third spacing dehydration DKA primary adrenal insufficiency How is hypervolemic hypotonic hyponatremia tx? - correct answer water restriction consider diuretics cortisol replacement w/ adrenal insufficiency
Iatrogenic How does hyperkalemia present? - correct answer nausea, vomiting intestinal colic areflexia weakness What can be seen on EKG that suggest hyperkalemia? - correct answer tall, peaked T waves; wide QRS; PR prolongation, loss of P waves. Can progress to sine waves, VFib, and cardiac arrest What happens if hyponatremia is tx too rapidly? - correct answer central pontine myelinolysis How is hyperkalemia tx? - correct answer K>6.5 needs treatment
- calcium gluconate for cardiac cell membrane stabilization
- bicarb and/or insulin and glucose to temporarily shift potassium into cells
- B- agonists to promote cellular reuptake of K
- eliminate K from diet and IV fluids
- Kayexalate to remove K from the body Dialysis for renal failure or severe, refractory cases What are causes of hypokalemia? - correct answer Transcellular shifts
- insulin
- B2 agonists
- alkalosis
- familial hypokalemic periodic paralysis GI losses
- diarrhea, chronic laxative abuse, vomiting, NG suction Renal losses
- diuretics (loop/thiazide)
- primary mineralocorticoid excess or 2ndary hyperaldosteronism
- decreased circulating volume
- Bartter's and Gitelman's syndromes
- Drugs: gentamicin, amphotericin
- DKA
- hypomag
- type I RTA (defective distal H+ secretion)
- polyuria How do pts with hypokalemia present? - correct answer fatigue, muscle weakness or cramps, ileus, hypotension, hyporeflexia, parethesias, rhabdomyolysis, and ascending paralysis What EKG signs indicate hypokalemia? - correct answer T wave flattening, U waves, ST segment depression, leading to AV block and subsequent cardiac arrest How is hypokalemia tx? - correct answer Tx underlying disorder Oral/IV K repletion. DO NOT exceed 20mEq/L/hr Replace Mg Monitor EKG and K What is the relationship btw K and digoxin? - correct answer hypokalemia sensitizes the heart to digitalis toxicity b/c K and digitalis compete for the same sites on the N/K pump, so if a pt is on digitalis, K levels must be carefully monitored What are the most common causes of hypercalcemia? - correct answer hyperparathyroidism malignancy What are other causes of hypercalcemia? - correct answer Calcium supplementation Hyperparathyroidism/hyperthyroidism
AVOID: thiazide diuretics, which increase tubular reabsorption of calcium What are the causes of hypocalcemia? - correct answer hypoparathyroidism (postsurgical idiopathic) malnutrition hypomagnesemia acute pancreatitis vitamin D deficiency pseudohypoparathyroidism In infants, what is a possible cause of hypocalcemia? - correct answer DiGeorge syndrome (tetany shortly after birth; absence of thymic shadow How does hypocalcemia present? - correct answer Abd muscle cramps dyspnea tetany perioral and acral paresthesias and convulsions Facial spasm (Chvostek's sign) carpal spasm after arterial occlusion by BP cuff (Trousseau's sign) What condition should be considered in this classic presentation? Pt develops cramps and tetany after thyroidectomy? - correct answer hypocalcemia What should be considered in lab values when serum calcium is low? - correct answer check albumin serum Ca may be falsely look in hypoalbuminemia check ionized calcium What is the work-up of hypocalcemia? - correct answer ionized Ca 2+, Mg2+, PTH, albumin, possibly calcitonin post-thyroidectomy pts (check # of parathyroid glands removed)
What on EKG can be seen in hypocalcemia? - correct answer prolonged QT interval How is hypocalcemia tx? - correct answer Treat underlying disorder Mg repletion admin oral calcium supplements; give IV calcium for severe symptoms What are causes of hypomagnesemia? - correct answer <1.5mEq/L Decreases intake:
- malnutrition
- malabsorption
- short bowel syndrome
- TPN Increased loss:
- diuretics
- diarrhea
- vomiting
- hypercalcemia
- drugs (aminoglycosides, amphotericin)
- alcoholism
- kidney losses (recovering ATN, postosbstructive diuresis) Miscellaneous
- DKA
- pancreatitis
- extraclullar fluid volume expansion How does hypomagnesemia present? - correct answer usually concurrent hypocalcemia and hypokalemia
- anorexia, nausea, vomiting, muscle cramps, weakness SEVERE Sx
- lactic acidosis
- ethylene glycol
- salicylates What is renal tubular acidosis? - correct answer decrease in either tubular H+ secretion or HCO3- reabsorption that leads to a non-anion gap metabolic acidosis. RTA IV is most common What are the three types of acute renal failure? - correct answer Prerenal
- decreased renal perfusion Intrinsic
- injury w/in the nephron unit Postrenal
- urinary outflow obstruction
- both kidneys must be obstructed before one can see a significant increased BUN/CR How does acute renal failure present? - correct answer Sx of Uremia
- malaise
- fatigue
- confusion
- oliguria
- anorexia
- nausea Exam:
- pericardia rub
- asterixis
- HTN
- decreased UOP
- increased RR (compensation of metabolic acidosis or from pulmonary edema secondary to volume overload)
How does prerenal acute renal failure present? - correct answer thirst orthostatic hypotension tachycardia decreased skin turgor dry mucous membranes reduced axillary sweating stigmata of comorbid conditions How does intrinsic acute renal failure present? - correct answer assoc w/ hx of drug exposure (amnoglycosides, NSAIDs) Infection exposure to contrast media of toxins (myoglobin, myeloma protein) hematuria/tea-colored urine foamy urine (from proteinuria) HTN edema How does atheroemobli causing renal failure present? - correct answer subcutaneous nodules livedo reticularis digital ischemia How does postrenal acute renal failure present? - correct answer prostatic disease decreased UOP leading to suprapubic pain distended bladder and flank pain How is acute renal failure worked up? - correct answer Check COMP UA for RBCs, WBCs, casts, urine eosinophils FeNa <1%, Una <20, BUN/Cr >20, urine specific gravity >1.020 suggests prerenal etiology
What are the causes of RTA Type I? - correct answer hereditary cirhossis autoimmune disorders (Sjorgren's syndrome, SLE) Hypercalciuria Sickle Cell disease drugs (lithium, amphotericin) What are the causes of RTA Type II? - correct answer Hereditary (idiopathic or part of Fanconi's or cystinosis) drugs (carbonic anhydrase inhibitors) heavy metal poisoning vitamin D deficiency What are the causes of RTA Type IV? - correct answer Primary aldosterone deficiency hyporeninemic hypoaldosteronism (e.g. from kidney disease, ACEIs, NSAIDs) drugs (amiloride, spironolactone, heaprin) pseudohypoaldosteronism How is RTA Type I tx? - correct answer K citrate How is RTA Type II tx? - correct answer K citrate How is RTA Type IV tx? - correct answer furosemide, mineralocordicoid +/- glucocorticoid replacement, low K diet in pts w/ aldosterone deficiency What are complications of RTA Type I? - correct answer nephrolithiasis What are complications of RTA Type II? - correct answer rickets, osteomalacia
What are complications of RTA Type IV? - correct answer hyperkalemia What are the causes of prerenal ARF? - correct answer hypovolemia
- hemorrhage
- dehydration
- burns Cardiogenic shock
- decreased CO Systemic vasodilation
- sepsis
- burns Anaphlaxis Drugs
- ACEI
- ARBs
- NSAIDs Renal artery stenosis Cirrhosis w/ ascites
- hepatorenal syndrome What are the causes of intrinsic renal failure? - correct answer ATN Acute/allergic interstitial nephritis Glomerulonephritis Thromboembolism Renovascular disease (HUS/TTP, scleroderma) What are the causes of postrenal renal failure? - correct answer prostatic disease nephrolithiasis pelvic tumors
Overload (fluid) Uremic Sx (pericarditis, encephalopathy, bleeding, nausea, pruritus, myoclonus) What are the complications of ARF? - correct answer Metabolic acidosis-->hyperK leading to arrhythmias HTN (from renin hypersecretion) Volume overload leading to CHF and pulmonary edema CKD: needing dialysis What are the most common causes of CKD? - correct answer DM HTN glomerulonephritis Others
- PCKD (autosomal dominant form = adult, autosomal recessive = children) How does CKD usually present? - correct answer generally ASx until GFR < gradually begin to experience s/sx of uremia
- anorexia
- n/v
- uremic pericarditis
- "uremic frost"
- delirium
- seizures
- coma How is CKD dx? - correct answer Labs (notice metabolic derangements)
- Azotemia (increased BUN/Cr)
- Fluid retention (HTN, edema, CHF, pulmonary edema)
- metabolic acidosis
- hyperK
- anemia of chronic disease (decreased EPO)
- hypocalcemia, hyperphosphatemia (decreased phosphate excretion, impaired vitamin D production leading to renal osteodystrophy) How is CKD tx? - correct answer Pharma
- ACEI/ARBs and HTN control
- EPO analogs for anemia
- fluid restriction w/ low Na/K/phosphate intake
- oral phosphate binders and calcitriol for renal osteodystrophy Dialysis
- hemodialysis
- peritoneal dialysis
- renal transplantation What is the site of action and mechanism of carbonic anhydrase inhibitors? - correct answer (acetazolamide)
- proximal convoluted tubule
- inhibits carbonic anhydrase, increase H+ reabsorption, block Na/H+ exchange What are the SE of carbonic anhydrase inhibitors? - correct answer hyperchloremic metabolic acidosis sulfa allergy What are the sites of action and mechanism of osmotic agents? - correct answer (mannitol, urea)
- entire tubule
- increased tubular fluid osmolarity What are the SE of osmotic agents? - correct answer pulmonary edema due to CHF and anuria
How is GN dx? - correct answer UA: hematuria possibly proteinuria decreased GFR, elevated BUN and Cr Check: ANA, ANCA, anti-GBM ab levels Renal bx What are the different causes of GN? - correct answer postinfectious glomerulonephritis IgA nephropathy (Berger's disease) Wegener's granulomatosis Goodpasture's syndrome Alport's syndrome What are the dx clues to indicate postinfectious GN? - correct answer recent group A strep infxn (2-6wks prior) oliguria, edema, HTN, tea/cola-colored urine low serum C3 that normalizes 6-8wks after presentation increased ASO titer lumpy-bumpy immunofluorescence How is postinfectious GN tx? - correct answer supportive tx What are the dx clues to indicate IgA nephropathy/Berger's disease? - correct answer MOST COMMON TYPE assoc w/ URI/GI infxn Young males, may seen in HSP episodic gross hematuria or persistent microscopic hematuria Normal C How is IgA nephropathy tx? - correct answer glucocorticoids ACEI in pts w/ proteinuria 20%-->ESRD
What are the dx clues for Wegener's granulomatosis? - correct answer granulomatous infxn of respiratory tract w/ kidney necrotizing vasculitis fever, weight loss, hematuria, hearing disturbances, respiratory and sinus sx Cavitary pulmonary lesions bleed and lead to hemoptysis c-ANCA positive renal bx shows segmental necrotizing GN w/ few immunoglobulin deposits on immunofluorescence How is Wegener's tx? - correct answer high dose corticosteroids and cytotoxic agents pts tend to have frequent relapses What are the dx clues for Goodpasture's syndrome? - correct answer rapidly progressing GN w/ pulmonary hemorrhage; peak incidence in males in mid 20s hemoptysis, dyspnea, possible respiratory failure linear anti-GBM deposits on immunofluoresence iron deficiency anemia hemosiderin-filled Mphage in sputum pulmonary infiltrates on CXR How is Goodpasture's tx? - correct answer plasma exchange tx pulsed steroids may progress to ESRD What are the dx clues for Alport's syndrome? - correct answer Hereditary GN in boys 5--20yrs ASx hematuria assoc w/ nerve deafness and eye disorders GBM splitting on electron microscopy How is Alport's syndrome tx? - correct answer progresses to renal failure
