Renal Part 4

Renal Kidney Anatomy Proximal Tubule: reabsorption of Na, Cl, HCO3, glucose, hydrogen, phosphates, calcium, etc. -resabsorbs everything (all electrolytes), including the kitchen sink -if you body thinks you're low in K, Na, Cl, etc., your body will reabsorb it Loop of Henle: concentration and diluation of urine Distal Convoluted Tubule: site of ADH control (where ADH works to make your kidneys hold on to water) Acute Renal Failure -decrease in urine output less than 400 cc in 24 hours -3 stages of ARF: Pre-renal vs Renal Failure vs Post Renal stage of Acute Renal Failure Post-Renal Stage -you make urine, but it doesn't come out -ex. Benign prostatic hypertrophy -not a kidney problem, more of a urological problem Pre-Renal Stage -decrease in urine output (less than 400 cc/24 hours) due to decreased blood supply to kidneys -hypovolemia, CHF Renal Stage -decrease in urine output (less than 400 cc/24 hours) due to kidney damage (damaged tissues or nephrons) -acute tubular necrosis (ATN) = damage to nephron -50% mortality rate, 25% of those 50 need HD, only 25% unaffected without being dialysis dependent -caused by ischemia, nephrotoxicity (aminoglycosides, contrast, heavy metals, cephalosporins) -if caused by ischemia: hemorrhage, burns, sepsis, heart failure, transfusion reactions) -if caused by nephrotoxicity: heavy metals, medications, street drugs, rhabdomyolosis (breakdown of muscle), contrast dye -SO correct hypotension right away, before it develops from pre-renal to renal stage Acute Tubular Necrosis: Stages Oliguric Stage -lasts 7-10 days (barely putting out urine) -increased BUN, Creatinine, Potassium -fluid overload → CHF -peritoneal dialysis Polyuric Stage -lasts 2 weeks to 3 months -making a ton of urine → good quantity, bad quality -don't be fooled by a lot of urine in the foley bag -increased BUN, creatinine -low potassium (leak potassium out of damaged nephrons) -fluid depleted Recovery Stage -lasts 3 months to 1 year *pray that the kidneys regenerate themselves! -if not → dead or HD Acute Renal Failure: Pre vs Renal (ATN) How can you tell?? Normal Urinary Sodium = 40-100 Pre-Renal: Urinary Sodium = <20 (not enough blood getting to kidney, kidney holds on to water to increase intravascular volume so that more blood gets to kidney) -if you are in heart failure, it is a viscious cycle- you don't have enough blood getting to kidney but kidney wants more blood so it makes you hold on to water and worsens CHF -if not enough volume down to kidney, kidney holds on to water AND salt → worsens CHF -so when kidney holds on to water and salt → no salt in the foley bag -urinary sodium less than 20 means kidney is holding on to water to compensate for low intravascular volume Renal (ATN): Urinary Sodium = 40-100 -abnormal value if there's no urine in the foley bag -normal value if you have a normal amount of urine -damaged nephrons are leaking sodium out **SO... you can tell if they are in pre-renal or the oliguric stage of renal by the urine sodium level OR... Pre-Renal: BUN:Creatinine is 20:1 Renal (ATN): BUN:Cr is 10:1 OR.... Lasix or Fluid Challenge Pre-Renal failure- responds to lasix or fluids, puts out urine Renal- does not respond to lasix or fluids, does not put out urine Hyperkalemia -muscle weakness and EKG changes -peaked T wave (6.5-6.8) -prolonged P-R interval (7.0) -lose your P wave → >7.0 -then, widened QRS -biphasic (about 8.0) -sine wave (>8.0)= signing off -stopping steroids can cause adrenal insufficiency which causes hyperkalemia and hyponatremia *Treatment = Calcium Chloride (ONLY if there is EKG involvement → does not lower K level, but allows electricity to go through the heart normally- protects your heart) -Insulin + Glucose = pushes and hides K in cell, need to give glucose with the insulin so you don't become more hypoglycemic -Sodium Bicarb − K-Excelate = antidote Calcium and Phosphate -reciprocal relationship (when Ca is low, Phos is high, etc.) -people with kidney disease always have a low calcium level -kidneys make vitamin D → you need vitamin D to reabsorb calcium from your gut -people with kidney disease don't make vitamin D and can't absorb calcium from the gut, so... -kidney disease → hypocalcemia, hyperphosphatemia -if you give amphogel or vasogel (antacid) to coat stomach, it binds with phosphate and brings phosphate level down, so calcium level will increase -clinical manifestations of hyperphosphatemia: chvostek's sign (because hyperphosphatemia is the same as hypocalcemia), the signs of hyperphosphatemia are the same signs as hypocalcemia (twitch, twitch, seize, seize, chvostek and trousseau) -hypercalcemia/hypophosphatemia = severe muscle weakness ex. her brother in law with tums → became very week and lethargic, weight loss from high calcium levels of overingestion of calcium/ low phosphate (antacid binds with phosphate) Practice Questions 1) A weight gain of one kilogram in 24 hours may indicate fluid retention of at least: -1,000 mL 2) Signs of rapidly developing alkalosis include ALL BUT WHICH of the following: -obtundation -alkalosis = low calcium level -hypocalcemia = nervous irritability, muscle tremors, seizures 3) Which of the following drugs actually removes potassium from the body in hyperkalemic patients in acute renal failure? -Kayexalate and sorbital 4) The electrolyte abnormality that produces a U wave, depressed ST segment, and ventricular irriability is: -Hypokalemia 5) Which EKG finding would NOT be observed in the presence of hyperkalemia? -Ventricular irritability -hyperkalemia = prolonged PR interval, absence of P waves, widened QRS complexes 6) The glomerular filtration rate (GFR) can be best measured by evaluating the patient's: -Creatinine clearance 7) Approximately 60-80% of sodium and water is reabsorbed from the glomerular filtrate at the: -proximal tubule 8) The major function of the loop of Henle is: -Concentration or dilution of urine 9) What activity is performed at the distal convoluted tubule? -water reabsorption under ADH control 10) A patient has a urinary output of 1000 cc in 24 hours with a urine sodium of 25 mEq/liter. These findings indicate: -the patient is on a salt-free diet 11) Ischemic injury to the kidney will usually commence when the mean arterial blood pressure (MAP) falls below: -60 mmHg for 40 minutes 12) The two most common causes of acute renal failure or ATN are: -nephrotoxic substances and ischemia 13) The patient with acute tubular necrosis is differentiated from a patient with decreased renal perfusion because ONLY in decreased renal perfusion: -the BUN to creatinine ratio is 20:1 14) The oliguric state of acute renal failure WOULD NOT include which of the following: -BUN of 20 mg -would include: signs of CHF, K of 7 (because not making any urine), Creatinine 9 15) In ATN, caused by nephrotoxic drugs, Lasix will: -increase toxicity