Renal
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  • Hyponatremia (136): Low blood sodium (Na < 136) causes cerebral edema leading to neuro problems (confusion, seizure, coma).
    • Dehydration: orthostatic hypotension, BUN↑, but normal creatinine.
      • Sweat/diarrhea: lose both Na and H2O (initially Na++), but compensation makes Na-- (drinking, ADH).
    • Edema
      • CHF: exertional dyspnea, JVD, peripheral edema, elevated BNP, can be chronic or acute decompensated.
      • Cirrhosis: portal hypertension (varices, splenomegaly), skin (jaundice, spider angiomata, palmar erythema), ascites, coagulopathy, hx of EtOH, hepatitis, LFTs↑, dx w US and biopsy.
      • Nephrotic syndrome (lipiduria): proteinuria (edema, albumin↓) and lipiduria (fat casts, hyperlipidemia).
    • SIADH: Hyponatremia with natriuresis (urine Na > 40), no edema or dehydration.
    • Small cell lung carcinoma: smoker, central mass, biopsy shows small, blue cells, paraneoplastic syndromes (SIADH, ACTH/Cushings).
    • Hyperglycemia: cellular water dilutes blood sugar (and Na).
    • Pseudohyponatremia: hyperproteinemia, hyperlipidemia
  • Hypokalemia (U-wave): not enough extracellular K (<3.5) for repolarization, so neuro symptoms (muscle weakness, cardio arrhythmias), EKG shows U waves after T.
    • Redistribution: cellular uptake (insulin, beta2, alkalosis)
    • Aldosteronism: refractory hypertension, hypokalemia, metabolic alkalosis, aldo↓ even w salt loading, tx w eplerenone.
    • Diuretic abuse: fatigue, weakness, hypokalemia, urine K↑, due to loop diuretics (furosemide), thiazides.
    • Na retention: increased renin/AT/aldosterone (Aldosteronism)
  • Hyperkalemia: too much K (K > 5) causing neuro: muscle (weak/paralyze), cardio (slow, irregular, blocks), EKG shows T↑, QT↓, wide QRS if severe, tx w Ca.
    • Redistribution: lysis (K out of cells), digoxin (blk Na-K pump), less cellular uptake (no insulin, beta2 blk, acidosis).
    • Hypoaldosteronism: Hyperkalemia, hyponatremia, hypotension.
    • Na excretion: decreased renin/AT/aldosterone (spirinolactone), Hypoaldosteronism
    • K sparing diuretics: ENaC blk (amiloride), aldosteron antag (spirinolactone)
    • low GFR: no Na reaches collecting duct to counterexchange potassium
    • Pseudohyperkalemia: high platelets, WBCs cause artificial hyperkalemia, do a serum measurement.
  • Metabolic acidosis: pH < 7.4, HCO3 < 24.
    • Diarrhea: lose Na bicarb
    • Proximal RTA: proximal tubule don't reabsorb bicarb, nl anion gap metabolic acidosis, hx of Fanconi's syndrome.
    • Distal RTA: distal tubule can't secrete H, nl anion gap metabolic acidosis, hypokalemia, stones, bone demineralization.
    • High anion gap
      • Ethylene glycol poisoning (acidosis): high anion gap acidosis due to glycolate and NADH, tx with EtOH and dialysis..
      • Methanol poisoning (blind): formate causes blindness and high anion gap acidosis.
      • Lactic acidosis (lactate > 5): Too much lactic acid because of hypoperfusion (lung dz, exercise), drugs.
      • Ketoacidosis (fruity): Ketone bodies++ (high anion gap metabolic acidosis) due to diabetes, alcoholism, starvation - breath smells fruity (acetone).
      • Aspirin poisoning: aspirin causes hyperpnea (early resp alkalosis), decouples oxidative phosphorylation (late metabolic acidosis, hyperthermia) and other toxicities (tinnitis, creatinine/renal) - give bicarb.
      • Other acidoses: pyroglutamic/oxoproline (acetaminophen, malnutrition)
  • Respiratory acidosis (hypoventilation): pH < 7.4, pCO2 > 40.
  • Metabolic alkalosis: pH > 7.4, HCO3 > 24.
    • Aldosteronism: refractory hypertension, hypokalemia, metabolic alkalosis, aldo↓ even w salt loading, tx w eplerenone.
    • Vomiting: vomit out HCl, so metabolic alkalosis with low blood and urine Cl.
    • Excess base administration: bicarb, citrate, antacid
  • Respiratory alkalosis (hyperventilation): pH > 7.4, pCO2 < 40 bcz of hyperventilation.
  • High anion gap with normal pH
    • Isopropanol poisoning: drunk, high anion gap without acidosis.
    • Mannitol, Dextran-40
  • Nephrotic syndrome (lipiduria): proteinuria (edema, albumin↓) and lipiduria (fat casts, hyperlipidemia).
    • Minimal change disease: kids with nephrotic syndrome and normal glomerulus light microscopy, tx with steroids, ACE inhibitors.
    • Membranous nephropathy: nephrotic syndrome due to subepithelial immune complex deposits, with a tendency to clot.
    • FSGS: nephrotic syndrome with glomerular sclerosis (focal and segmental).
    • Diabetic nephropathy: diabetic with nephrotic syndrome and KW nodules on renal biopsy.
    • Amyloidosis: M protein LC (immunofix) forms amyloids (congo red/apple green) that mess up organs (renal, liver, cardio, neuro, tongue, MSK).
  • Nephritic syndrome (hematuria): dysmorphic hematuria, red casts, proteinuria, hypertension, azotemia.
    • Poststrep GN: recent (weeks) strep infection (antistrep/ASO), nephritic (dysmorphic hematuria, red casts), biopsy shows glomerular hypercellularity with PMNs, subepithelial humps, alternate pathway (C3↓, nl C4).
    • Alport's syndrome: hematuria and hearing loss due to bad collagen (skin biopsy lack alpha5, renal biopsy shows thick/frayed GBM).
    • MPGN: mixed nephrotix/nephritic, membrano (thick glomerular capilaries), mesangial proliferative (glomerular hypercellularity), alternate pathway (low C3, normal C4).
    • RPGN: nephritic (hematuria, red casts) with severe proteinuria and kidney failure (GFR--, oligouria) due to crescent scars (leaked fibrin -> inflammation) in glomeruli.
      • Anti-GBM: linear immunostaining
        • Goodpasture's syndrome: Lung (SOB, hemoptysis, diffuse opacities), Renal (hematuria) and fatigue due to anti-GBM - renal biopsy shows crescents and IgG deposition.
      • Immune complex: granular immunostaining
        • HSP: kids with purpura, arthritis, abdominal pain and renal symptoms due to IgA deposition - confirm with skin (vasculitis) and renal (mesangial deposition) biopsy.
        • IgA nephropathy (URTI): frank hematuria a day after a respiratory (IgA) infection, renal biopsy shows IgA staining on mesangium.
        • Lupus: buttefly rash, photosensitivity, fatigue, joint pain (hands) and a whole bunch of organ systems involved - dx by ANA and anti-dsDNA antibodies.
        • Cryoglobulinemia: Vasculitis (cryoglobulins) causing purpura (legs), MSK (arthralgia, weakness), and renal (proteinuria, hematuria), classic pathway (C3↓, C4↓).
      • Pauci-immune: ANCA, lack immunostaining
        • GPA (Wegener's): ENT (sinusitis, crusting), pulm and renal (hemoptysis, hematuria), vasculitis (purpura), due to ANCA, perivascular granulomas, glomerular crescents without immune deposits.
        • CSS: Asthma, rhinitis, nodules/purpura, eosinophilia (blood, lung, extravascular), neuropathy, pulm opacity, hematuria.
        • MPA: purpura, ENT inflammation, pulm dz, hematuria, glomerular crescent, pauci-immune, no granuloma or asthma.
  • Hemoptysis
    • Goodpasture's syndrome: Lung (SOB, hemoptysis, diffuse opacities), Renal (hematuria) and fatigue due to anti-GBM - renal biopsy shows crescents and IgG deposition.
    • Lupus: buttefly rash, photosensitivity, fatigue, joint pain (hands) and a whole bunch of organ systems involved - dx by ANA and anti-dsDNA antibodies.
    • Cryoglobulinemia: Vasculitis (cryoglobulins) causing purpura (legs), MSK (arthralgia, weakness), and renal (proteinuria, hematuria), classic pathway (C3↓, C4↓).
    • ANCA vasculitis: vasculitis (purpura, hemoptysis), pauci-immune renal immunostain, GPA (granuloma), CSS (asthma, eosinophilia) and MPA (no granuloma or asthma).
  • Alternate pathway: Low C3, nl C4
    • Poststrep GN: recent (weeks) strep infection (antistrep/ASO), nephritic (dysmorphic hematuria, red casts), biopsy shows glomerular hypercellularity with PMNs, subepithelial humps, alternate pathway (C3↓, nl C4).
    • MPGN: mixed nephrotix/nephritic, membrano (thick glomerular capilaries), mesangial proliferative (glomerular hypercellularity), alternate pathway (low C3, normal C4).
  • Classic pathway: Low C3, low C4
    • Lupus: buttefly rash, photosensitivity, fatigue, joint pain (hands) and a whole bunch of organ systems involved - dx by ANA and anti-dsDNA antibodies.
    • Cryoglobulinemia: Vasculitis (cryoglobulins) causing purpura (legs), MSK (arthralgia, weakness), and renal (proteinuria, hematuria), classic pathway (C3↓, C4↓).
  • Skin manifestations: rash, purpura, etc
    • HSP: kids with purpura, arthritis, abdominal pain and renal symptoms due to IgA deposition - confirm with skin (vasculitis) and renal (mesangial deposition) biopsy.
    • Lupus: buttefly rash, photosensitivity, fatigue, joint pain (hands) and a whole bunch of organ systems involved - dx by ANA and anti-dsDNA antibodies.
    • Cryoglobulinemia: Vasculitis (cryoglobulins) causing purpura (legs), MSK (arthralgia, weakness), and renal (proteinuria, hematuria), classic pathway (C3↓, C4↓).
    • ANCA vasculitis: vasculitis (purpura, hemoptysis), pauci-immune renal immunostain, GPA (granuloma), CSS (asthma, eosinophilia) and MPA (no granuloma or asthma).
    • Atheroembolism: Skin (livedo reticularis), renal (subacute renal impairment), eosinophilia (early on).
    • Fabry's disease: ab angiokeratomas, hand pain, proteinuria, renal insufficiency, xlink FHx (male).
  • Pediatrics
    • HSP: kids with purpura, arthritis, abdominal pain and renal symptoms due to IgA deposition - confirm with skin (vasculitis) and renal (mesangial deposition) biopsy.
    • Minimal change disease: kids with nephrotic syndrome and normal glomerulus light microscopy, tx with steroids, ACE inhibitors.
    • Congenital: obstructions (hydronephrosis), malformations
      • Potter's syndrome: Renal problems causes oligohydramnios, facial/ear squishing, limb deformities.
      • MCKD: infant abdominal mass, dx by ultrasound.
      • ARPKD: Enlarged smooth kidneys without cysts, pulmonary hypoplasia in infants, dx by ultrasound.
      • PUV: Hydronephrosis, dilated bladder, posterior urethra dilated, male, dx with voiding cystourethrogram.
      • VUR: Urine backleaks from bladder to upper urinary track, causing hydronephrosis, dx by voiding cystourethrogram.
      • UVJ obstruction: hydronephrosis from obstruction in ureter-bladder junction, dx by ultrasound.
      • UPJ obstruction: abdominal mass, hydronephrosis dx by ultrasound.
      • Ureterocele: distal ureter balloons, UTI risk, dx by ultrasound.
  • Hydronephrosis
    • Kidney stone: Unilateral flank pain, hematuria, hydronephrosis dx by CT.
    • BPH: Voiding problems, enlarged smooth, nontender prostate, biopsy shows normal glands, tx with alpha1 blockers.
    • Prostate cancer: Voiding problems, PSA↑, bump/lump on recal exam, dx by needle biopsy.
    • Congenital obstructions
  • Hematuria
    • Glomerular (nephritic): dysmorphic, has red casts, proteinuria
    • Non-glomerular: monomorphic, has clots
      • ADPKD: Flank pain, gross hematuria (esp after trauma), large kidneys with multiple cysts, hypertension, tx w ACE inh.
      • Renal cell carcinoma: Flank pain, gross hematuria, nontender abdominal mass, wt loss, dx w US (irregular echogenic mass) and CT (enhancing).
      • Kidney stone: Unilateral flank pain, hematuria, hydronephrosis dx by CT.
      • Bladder cancer: painless, gross monomorphic hematuria, voiding problems, wt loss, hx of smoking or carcinogen exposure, dx with cystoscopy.
      • UTI: burning urination, frequency/urgency, hematuria, cloudy urine, cystitis (most common), pyelonephritis (fever, flank pain).
      • Cystitis: painful urination, frequency/urgency, cloudly urine, hematuria, WBCs, urine culture+.
      • Pyelonephritis: Fever, ab/flank pain, painful urination, white casts, PMNs.
    • Other hematuria
      • Rhabdomyolysis: myalgia, dark urine, myoglobinuria (dipstick/heme+, but no RBCs), hyperkalemia, CK↑.
  • Hypoperfusion
    • Ischemic ATN: hypoperfusion causes renal tubular damage: loss of brush border, Tamm-Horfall protein in tubule, muddy brown cast.
    • HRS: Cirrhosis with ascites presents with renal failure, tx with albumin.
  • Drugs/toxins
    • Nephrotoxic ATN: drugs/toxins (aminoglycoside) causing tubular damage: cellular debris in tubules, muddy brown casts.
    • AIN: allergic reaction to drugs damage kidneys, biopsy shows interstitial infiltration of mononuclear WBCs and eosinophils.
    • Contrast-induced nephropathy: Rise in creatinine a day or two after giving iodinated contrast to a patient with low GFR.
  • White casts
    • AIN: allergic reaction to drugs damage kidneys, biopsy shows interstitial infiltration of mononuclear WBCs and eosinophils.
    • Pyelonephritis: Fever, ab/flank pain, painful urination, white casts, PMNs.
  • Voiding problems
    • Prostate
      • Acute bacterial prostatitis: fever/chills, urine troubles, pelvic pain, boggy prostate, urine PMNs, bacteria, tx w quinolones.
      • Chronic bacterial prostatitis: urine troubles, pelvic pain, no fever/chills, urine mononuclear WBCs, bacteria, tx w quinolones.
      • Chronic nonbacterial prostatitis: Urine troubles, pelvic pain, but no bacteria.
      • BPH: Voiding problems, enlarged smooth, nontender prostate, biopsy shows normal glands, tx with alpha1 blockers.
      • Prostate cancer: Voiding problems, PSA↑, bump/lump on recal exam, dx by needle biopsy.
    • Bladder
      • Bladder cancer: painless, gross monomorphic hematuria, voiding problems, wt loss, hx of smoking or carcinogen exposure, dx with cystoscopy.
      • Overactive bladder: Urgency, frequency, nocturia, tx w anticholinergics.
      • Bladder not contracting: slow urine, retention, tx with catheter
    • Outlet
      • Stress incontinence: Urine leaks out when coughing, sneezing, laughing, due to weak pelvic floor muscles, tx with pelvic sling.
      • Outlet overcontractility: slow urine, retention, tx with catheter, physical therapy
  • Testicular problems
    • Orchitis: Testis pain, hx of Mumps, STDs.
    • Epididymitis: Testis pain, swollen epididymis.
    • Testicular torsion: Testis pain, horizontal testis, dx by doppler US, tx as surgical emergency.
    • Cryptorchidism: Undescended testes.
    • Testicular cancer: Painless mass in testis, dull ache in lower ab, retroperitoneal metastasis.
  • Penis problems
    • Peyronie's disease: Penis not straight during erection due to fibrous plaques.
    • Condylomata acuminata: Genital warts caused by HPV.
    • Phimosis: foreskin can't retract.
    • STDs
    • Squamous cell carcinoma
  • Other
    • Light chain cast nephropathy: fractured cast in tubule, due to light chains in MM (bone/joint pain, anemia)
    • Thrombotic microangiopathy: schistocytes, HUS/TTP.
    • CKD: Diabetes and hypertension causes progressive renal failure: GFR↓, metabolic acidosis, nephrotic (proteinuria, lipiduria), bone resorption (PTH↑, PO4↑, VitD↓), anemia, tx with ACE inh, dialysis, transplant if GFR < 20.