Renal Flashcards
What % of total body weight is plasma volume? Interstitial fluid?
Plasma volume - 5%
Interstitial volume - 15%
(Total ECF is 20%)
What is the maximum serum glucose concentration that can be fully reabsorbed in the tubules?
350 mg/dL
What is exchanged for secretion of organic anions in the distal proximal tubule?
alpha-ketoglutarate
Where in the nephron is Mg reabsorbed?
Thick ascending limb
Where does PTH exert its action on the nephron?
Na/Ca channels in the early distal tubule
Indications for acetazolamide
Metabolic alkalosis (altitude sickness), glaucoma, pseudo tumor cerebri
Indications for mannitol
Shock, acute angle-closure glaucoma, and elevated ICP
pulls water out of tissues into vasculature + free water loss in kidneys
Do loop diuretics concentrate or dilute urine?
Dilute - even though you keep more ions in the tubule, since they are not reabsorbed into the nodular interstitium there is less water absorption in the thin descending limb = dilution
Why should aminoglycosides not be used with loop diuretics?
Both cause ototoxicity and nephrotoxicity
When should HCTZ be used: idiopathic calciuria or hyperparathyroidism?
Only in idiopathic calciuria because decreased Ca in the urine will only worsen the hypercalcemia in hyperparathyroidism
What are 3 other side effects of HCTZ?
Hyperglycemia, hyperlipidemia, and hyperuricemia (increases glucose, lipids, and uric acid)
What 3 diuretic classes are sulfa drugs?
Acetazolamide (carbonic anhydrase inhibitor), loop diuretics (except ethacrynic acid), and thiazides
What diuretic doesn’t increase urinary NaCl?
Acetazolamide
Pregnant mother given medications to stop preterm labor. Now has reduced DTRs, why?
IV Mg given to stop the uterine contractions, but hyperMg can also cause hyporeflexia
How does hypoMg affect an EKG?
Lengthens QT intercal, can cause TdP
What causes K to shift outside the cell = hyperK?
“Do Insulin LABs”
Digitalis (blocks Na/K ATPase), Insulin deficiency (DKA), Lysis of cells, Acidosis (Na/H pumps), B blockers
3 treatments for peaked T waves on EKG
HyperK = B agonist (shifts K into cells), bicarbonate (metabolic alkalosis), and dextrose + insulin
What 3 drugs are used to treat nephrogenic DI?
- Indomethacin (decrease RBF/GFR)
- HCTZ (volume contraction stimulates more water retention at the proximal tubule)
- IF Li induced - Amiloride (blocks Na channel Li uses to enter the principal cells)
What causes high anion gap metabolic acidosis?
“MUDPILES”
Methanol, uremia, DKA, propylene glycol, iron/isoniazid, lactic acid, ethylene glycol, and salicylates
What causes normal anion gap metabolic acidosis?
HCO3 loss - diarrhea, renal tubular acidosis, acetazolamide
HTN + hypoK + metabolic alkalosis
Primary hyperaldosteronism
Na - normal due to ANP activation
K - aldosterone promotes loss
HCO3 - aldosterone promotes H loss = HCO3 retention
What causes metabolic alkalosis?
Vomiting (H loss), loops/HCTZ (HCO3 retention), and hyperaldosteronism (HCO3 retention)
Normal ion gap metabolic acidosis + urine pH > 5.5 + hypoK +/- nephrocalcinosis/nephrolithiasis
Type 1 (distal) renal tubular acidosis - a-intercalated cells fail to secrete H "Type 1 = H" Acidosis activates aldosterone to increase H+ secretion but doesn't work = hypoK
Normal ion gap metabolic acidosis + urine pH
Type 4 (hyperkalemic) renal tubular acidosis - hypoaldosteronism "Type 4 = NH4, aldo" Low aldosterone = hyperK = decreased NH3 production in the proximal tubule = impaired filtrate H+ buffering = H retention
Normal ion gap metabolic acidosis + urine pH
Type 2 (proximal) renal tubular acidosis - failure to reabsorb HCO3 in the proximal tubule (Fanconi syndrome) "Type 2 = BIcarb" Urine pH still acidotic because HCO3 isn't made, stays as CO2 + H20 in the urine PO4 normally reabsorbed in the proximal tubule, but the entire PCT is nonfunctional so PO4 loss leads to rickets
Waxy casts in urine
Chronic renal failure
Hyaline casts in urine
Normal, concentrated urine
What is the most common type of kidney stone?
Ca (with oxalate or phosphate)
What are 3 causes of calcium kidney stones?
Ethylene glycol ingestion, vitamin C abuse, and Chron’s disease (saponification of fat within GI tract allows more oxalate to be absorbed = supersaturation in the kidneys)
Treatment for Ca kidney stones
HCTZ
What causes NH4-Mg-PO4 stones?
Struvite stones - urease + bacterial UTIs (Proteus mirabilis, klebsiella pneumoniae)
Where in the nephron does uric acid precipitate to form uric acid stones? Why?
Collecting ducts because this is where pH is lowest
What causes cysteine stones?
Cystinuria - genetic mutation that impairs intestinal and renal (proximal tubule) reabsorption of Cys, Ornithine, Lys, and Arg (COLA)
Treatment for cysteine stones
Alkalinize the urine (acetazolamide)
What 2 types of stones can form stag horn calculi (that fill the entire renal pelvis)?
Struvite and cysteine
Infant with cysts in both kidneys + cartilage on histology
What is the diagnosis?
What is the inheritance pattern?
Dysplastic kidney NOT inherited (de novo mutation)
Where are cysts found in PKD?
Cortex and the medulla
Infant with HTN and renal failure
ARPKD
What extra-renal findings are associated with ARPKD?
Hepatic cysts and congenital hepatic fibrosis
Newborn with portal HTN
ARPKD
HTN with increased plasma renin + hematuria + worsening kidney failure in young adults
ADPKD
What extra-renal findings are associated with ADPKD?
Hepatic cysts, berry aneurysms, and mitral valve prolapse
“Liver, brain, heart, and kidney cysts”
Bilateral shrunken kidneys with cysts
Medullary cystic disease (cysts are only in the medulla)
Autosomal dominant
Why is the BUN:creatinine ratio > 15 in pre-renal and post-renal azotemia?
Pre-renal = decreased RBF will activate RAAS, increased water reabsorption will pull BUN with it Post-renal = increased hydrostatic P in the tubules will force more BUN back into the blood
What are 5 causes of nephrotoxic acute tubular necrosis?
“Renal Endothelium Aggregates Like Mud” - muddy brown casts seen in ATN
Radiocontrast, ethylene glycol, aminoglycosides, lead, myoglobinuria
How does ATN affect K and acid-base status?
HyperK + increased anion gap metabolic acidosis
Due to decreased renal clearance of K and organic acids (also BUN and creatinine)
Eosinophils in the urine
Drug-induced interstitial nephritis
What are 4 causes of renal papillary necrosis?
NSAIDs - afferent arteriole constriction = decreased RBF (medulla susceptible to ischemia)
Sickle cell anemia OR TRAIT - high osmolarity in the medulla causes even heterozygous HbS cells to sickle = ischemia
DM and acute polynephritis
Pyuria with negative urine cultures
Chlamydia or gonorrhea
Scarring of the upper and lower poles of the kidney + blunted calyx + thyroidization of renal tissue
Chronic pyelonephritis (typically due to vesicourethral reflex) Thyroidization = proteinaceous material left within atrophic tubules forms pink casts
What type of kidney stone is NOT visible on Xray?
Uric acid stones
Pericarditis + increased bleeding time + asterixis + crystal deposition in skin
Uremia associated with chronic renal failure
Impeded platelet adhesion and aggregation
What cell type makes EPO?
Renal peritubular interstitial cells
What 4 paraneoplastic syndromes are associated with renal cell CA?
EPO, renin, PTHrp, and ACTH
What must be considered if a patient presents with a L sided varicocele?
RCC - propensity to invade the renal vein which could block venous drainage from the L testicular vein
What genetic mutation is associated with RCC?
Loss of VHL = increases IGH and HIF (TF for VEGF and PDGF)
What is the most important risk factor for sporadic RCC?
Smoking
What syndrome is associated with RCC?
What other cancer is associated with this syndrome?
Von Hippel Lindau (hence VHL gene)
Cerebellar hemangioblastoma
Wilms tumor + aniridia + genital abnormalities + mental/motor retardation
WARG syndrome
What is the histology of Wilms tumor?
Primitive renal precursors = “blastema”
May form primitive renal tubules and stroma, but primarily the small dark blue primitive cells
What genetic mutation is associated with flat urothelial CA?
Early p53 mutations
Why is urothelial multifocal with high recurrence rate?
Because the entire bladder is mutated from the exposure
What are the risk factors for urothelial CA?
“SAC”
Smoking, aniline dyes (hair dye), and cyclophosphamide
Young middle eastern male with painless hematuria
Bladder squamous cell CA secondary to Schistosome haematobium infection
What does a arches remnant put you at increased risk for?
AdenoCA at the dome of the bladder