Renal System


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Renal System

  1. 1. Pete A. Gutierrez MD, MMS, PA-C Miami Dade College Physician Assistant Program March 2009
  2. 2. GFR = UV/P  An Elevated >20:1 Bun/Cr. Ratio indicates  wither pre-renal azotemia Alkalemia increase in blood calcium level can  lead to diffuse paresthesias/numbness and muscle spasm. Formation of carbonic acid and dissociation  into HCO3 and CO2.
  3. 3. Anion Gap  ◦ Anion Gap normal is 12 ◦ Formula is AG = Na –(HCO3+CL) ◦ The anions in blood include HCO3, Cl, Phosphate, Sulfate, Albumin, and organic acids. ◦ The Cations include NA, K, Ca, Mg. ◦ Metabolic acidosis occurs with overproduction of lactic acid or ketoacids. ◦ It can also occur with HCO3 wasting or renal tubular acidosis or diarrhea. ◦ Underexcretion of acid (renal Failure) and also in poisonings by agents that are metabolized to acids.
  4. 4. Causes of increased anion gap metabolic  acidosis: ◦ Severe CRF decreased acid especially NH4 ◦ Ketoacidosis diabetic, alcoholic, starvation ◦ Lactic acidosis drugs, circulatory compromise ◦ Rhabdomyolysis ◦ Poisoning salicylates, methanol, ethylene glycol
  5. 5. Causes of normal anion gap acidosis:  ◦ Renal tubular acidosis ◦ Diarrhea ◦ Carbonic anhydrase inhibitors
  6. 6. Patients who drink methanol produce  formaldehyde and formic acid resulting in a high anion gap acidosis. Ethylene glycol (Antifreeze) forms glycolic acid  and oxalic acid resulting in a high anion gap acidosis and calcium oxalate crystals in the urine. Patients drinking isopropyl alcohol can have  significant ketosis without acidosis because isopropyl alcohol breaks down to acetone. So a patient arriving with stuporous and fruity  smell on his breath and has normal chemistry except high ketones.
  7. 7. These test should be preformed on a patient  who comes in with high anion gap acidosis: Urine + serum ketones levels ◦ Lactic acid level ◦ And the osmolar gap. ◦ The osmolar gap is the different between measured ◦ and calculated osmolarity. Calculated osmolatity is:  Osm = 2(NA) + BUN/2.8 + glucose/18  Normal osmolar gap is < 10.  If >20 think of intoxication with any one of the alcohols.
  8. 8. Metabolic Alkalosis:  Usually results from volume contraction  caused by diuretics or vomiting which causes a lost of HCL. Treatment requires KCL, and NaCl. 
  9. 9. Acid base Status  PH PCO2 PO2 Status Example  7.56 20 90 Alkalosis Hyperve  7.56 20 50 Alk Asthma  7.44 20 90 Chronic CNS  7.43 30 60 as above COPD  7.24 60 80 Acidosis Sedative  7.16 70 50 Acidosis Hypoxia  7.44 60 90 Alkalosis HCO3 
  10. 10. Normal Osmolality is usually 282+ or – 2  mosm/kg H2O. If glucose and Bun are normal just use the  (NA) x 2 to see if it is normal Low Na is the most common electrolyte  abnormality: ◦ Isotonic ◦ Hypertonic ◦ Hypotonic
  11. 11. Isotonic hyponatremia occurs when protein or  lipids displace sodium as in multiple myeloma (MM) and p hyperlipidemia. There is an increased osmolar  gap. The measured serum osmolality is normal while the calculated osmolality is low because of the low NA, Hypertonic both glucose an mannitol cause an  osmotic shift of water out of cells which dilutes plasma NA remember that for each 100 mg/dl increase in glucose, sodium concentrations decreases by 1.6.
  12. 12. Hypotonic:  The hypo tonicity cause intracellular swelling  which may result in neuromuscular excitability, seizures and coma. Usually when the NA goes below 120 the  sodium level decreases slowly the cells re- equilibrate and do not swell enough to cause these symptoms. The hypotonic group is further subdivide by  volume status: Low-High-Normal
  13. 13. The low-volume is the group of patients that  have lost both water and Na, but more Na than water this is normally caused by the use of diuretics, GI loses (Vomiting and Diarrhea) and adrenal insufficiency. In adrenal insufficiency, low aldosterone caused decreased active NA reapsortion which results in NA and water wasting, with high K and a mild metabolic acidosis.
  14. 14. Hypotonic High:  These people usually have low output CHF or  hypoalbuminemia (From Cirrhosis) they retain water and NA but usually more water than NA so they have normal or even elevated total body NA. Often these patients have edema and JVD.  Normal treatment is restriction of water and  NA. (Used loop diuretics).
  15. 15. Hypotonic (SIADH):  ◦ The normal volume patients usually have SIADH, but this can also be caused by psychogenic polydipsia (rare) and even by diuretics, if there is sufficient water replacement. ◦ The serum uric acid and bun are low but this is dilusional. ◦ The most serious causes of SIADH are CNS disorders to include meningitis, lung disorders, and cancer especially small cell carcinoma. ◦ Also cancer of the duodenum and thymus and some drugs like cyclophosphamide, clofibrate, and vincristine.
  16. 16. Treatment of Hyponatremia:  ◦ If the patient is hypovolemic give 1-2 liters of normal saline. ◦ If the symptoms are severe to include seizures give 3% saline, along with loop diuretics. ◦ Give the 3% saline over 8-12 hours, to increase the sodium by 10meg/lt. ◦ The meq is calculated by multiplying the total body water (60% of body weight eg 60 L in a 100 kg patient) by 10 which would equals 600 meq. ◦ Each liter of 3% saline has 512 meq of NA so about 1 liter could be given over 12 hours.
  17. 17. NEVER, Never, Never give hypertonic saline  rapidly. The correction should not exceed 1-2  mmol/hr. If the patient has SIADH treat with fluid  restriction and give Demeclocycline 900 mg/day. Osmotic demyelination syndrome, central  pontine myelinolysis so it is very important not to replenish the NA too quickly.
  18. 18. Hypernatremia:  ◦ This is fairly rare and only due to the patient not been able to get to water or the thirst mechanism is defective. ◦ Unlike hyponatremia patients these patients are always hyperosmolar. ◦ The amount of water needed to treat a hypernatremic patient is calculated by multiplying the total body water (60% of weight in Kg), by the fractional difference between the patient NA and normal NA.
  19. 19. Diuretics:  ◦ Proximal convoluted tubule (PCT) 90% of the HCO3 is reabsorbed here by means of several chemical changes. The reabsortion process is driven by H being secreted. ◦ A carbonic anhydrase inhibitor (acetazolamide (Diamox) causes diuresis with bicarbonate wasting resulting in a metabolic acidosis). ◦ Calcium is also absorbed in the proximal tubule. ◦ When treating severe hyperclacemia normal saline is infused at a high rate along with loop diuretics. ◦ The saline expands the volume and causes increased flow in the proximal tubules that prevents calcium reabsorption and the greatly increase calcium load then delivered to the distal tubule overwhelms the distal tubules ability to adsorb calcium and its ability is also block by the loop diuretics
  20. 20. Loop of Henle:  ◦ As the tubular fluid progresses down the loop of Henle free H2O is sucked out of the fluid following the osmotic gradient (The renal medulla is very hypertonic). ◦ At the base of the loop, the tubular fluid is maximally concentrated. ◦ In the ascending limb 25% of the filtered NaCl is actively reabsorbed . ◦ This increases the hyper tonicity of the medulla and causes H2O from the descending limb to effectively follow the NA out of the ascending limb. ◦ Blockage of this absorption of NA with loop diuretics results in diuresis.
  21. 21. The Distal Tubule:  ◦ This is where NA is actively reabsorbed and either H in the form of salts (NH4 or phosphate salts) or K are then excreted. ◦ They flow back down the electrical gradient caused by the reasorption of NA. ◦ This used to be called the NA-K pump but actually it is the NA pump—K/H electrical excretion gradient. ◦ Aldosterone facilitate this transport and an K sparing diuretic like triamterene our spironolactone.
  22. 22. Collecting Duct:  ◦ Is where ADH has its effect. ◦ In the normal kidney the urine is very dilute by the time is reaches the collecting duct. ◦ ADH increases the permeability of the collecting duct to water, allowing the free water to reabsorbed into the hypertonic renal medulla. ◦ There there is no ADH a very dilute urine is produced.
  23. 23. Minerals:  ◦K ◦ Even slight hyperkalemia stimulates the release of aldosterone which causes a normally function kidney to increased absorption of NA distally and there for increase excretion of K. ◦ Hyperkalemia is caused by decreased excretion (Drugs, renal failure, hypoaldosteronism such as Addison disease) increased production (trauma, tumor lysis) volume contraction in hospital more common. ◦ Drugs are probably the most common cause of increase K like ACE inhibitors and beta blockers.
  24. 24. The cardiac effects of hyperkalemia are due  to the large difference between intracellular and extracellular K levels. Treatment can be done with glucose +  Insulin. Can also give the patient IV calcium in the  form of Calcium Chloride 1 amp. Calcium Gluconate. 
  25. 25. Calcium regulation:  ◦ Regulation of calcium PTH and vitamin D metabolites cause changes in the way the kidney, GI, and bone handle calcium. ◦ Calcium circulates in an inactive form bound form (usually albumin) and an active form, called also ionized/unbound form. ◦ With hypoalbuminemia only the bound form decreases. ◦ For each decrease in albumin of 1, the total calcium will decrease by .7
  26. 26. Magnesium:  ◦ Hypomagnesaemia is rare and occurs from the use of Mg-containing laxatives or antacids in renal failure patients and MgSO4. ◦ Symptoms begin with levels of >4-6 meq/l. ◦ Symptoms level are sedation, muscle weakness, and a loss of deep tendon reflexes and can progress to paralysis.
  27. 27. Hyperphosphatemia:  ◦ Acute increase is from acute tubular necrosis, IV solutions, and tumor lysis after chemotherapy. ◦ Chronic increase in parathyroidism. ◦ Hypophosphatemia:  Think Alcohol if severe PO4< 1mg/dl it may cause rhabdomyolisis as also can low K.
  28. 28. Diuretics Medications:  Ethacrynic Acid ◦ Furosemide (Lasix ◦ Bumex ◦ Carbonic Anhidrase Inhibitors ◦ Triamterene ◦ Zaroxylin ◦ Mannitol ◦ Diazyde ◦ ACE ◦
  29. 29. HTN:  ◦ Primary Hypertension: 95% of all hypertension is primary (1.e. essential idiopathic.) The systolic and diastolic blood pressure (DBP) define the stages of HTN:  Stage I SBP 140-159 or DBP 90-99  Stage II SBP 160-179 or DBP 100-109  Stage III SBP>180 or DBP>110
  30. 30. Urinary System:  ◦ Structures:  Urethra  Urinary Bladder ◦ Ureters Kidneys  Renal pelvis  Mayor Calyces  Minor Calyces  Collecting Ducts  Nephrons 
  31. 31. Functions Include:  Formation of Urine ◦ Urine Storage ◦ Urine Elimination ◦ Removing Wastes and foreign Substances ◦ By: ◦  Glomerular Filtration  Tubular Reabsorption  Tubular Secretion
  32. 32. The breakdown of proteins produces amino  acids and the subsequent metabolism of amino acids produces nitrogenous wastes like ammonia. The Ammonia is converted in the liver into  less harmful Urea. The body accumulates excess ions of  sodium, chloride, potassium, hydrogen ions, sulfate and phosphate.
  33. 33. The role of the Urinary system is to maintain  a balance of these products and to remove the excesses from the blood. The urine consists of the metabolic waste of  urea, excess water, excess ions, and toxic wasted that may have been consumed with food.
  34. 34. Function’s of the Urinary System:  Excretion/Reabsortion ◦ Maintain blood volume and concentration ◦ pH regulation ◦ Blood Pressure-Renin which helps adjust filtration ◦ pressure. ◦ Erythropoietin-A hormone that stimulates red blood cell production ◦ Vitamin D Production convert vitamin D to its active form Calciferol.
  35. 35. The kidneys are paired organs that are  reddish in color and resemble kidney beans in shape. They are the size of a closed fist. They are located between the parietal  peritoneum and the posterior wall of the abdomen also known as the retroperitoneal space. The right kidney is slighly lower that the left.  The average kidney measures about 11.25cm  long and 5.0 to 7.5 cm wide.
  36. 36. Near the center of the kidney is a notch called the  Hilum through which the ureter leaves the kidney, and blood vessels, nerves, and lymph vessels also enter and exit the kidney’s. Three layers of tissue surround each kidney:  ◦ The innermost is the renal capsule (serves as barrier against infection) ◦ The second layer is the adipose capsule (Protects the kidney’s from blows, and hold the kidney’s in place). ◦ The outermost layer is the renal fascia which is connective tissue that anchors the kidney’s to their surroundings.
  37. 37. The Internal Anatomy of the Kidney’s:  ◦ A frontal section will reveal the outer area called the cortex , and an inter area called the medulla. ◦ Within the medulla there are 8-18 striated, triangular structures called the renal pyramids. ◦ The Nephrons are the functional units of the kidney’s. They regulate the composition and volume of blood and form the urine.
  38. 38. The Minor calyxes surrounds the tip of each  renal pyramid and joint to form the Major calyxes which them joint together to form the renal pelvis. The functional unit of the kidney’s are the  nephrons, which is a microscopic renal tubule which functions as a filter. As we age the kidney’s decrease in size. At  age twenty they weigh approximately 260 grams and by age 80 they weigh is approximately 200 grams.
  39. 39. The nephron begins as a double-walled globe  known as the Bowman’s Glomerular Capsule. This is located in the cortex of the kidney’s The right and left renal arteries transport one  quarter of the total cardiac output directly to the kidney’s. About 1200 ml of blood passes through the  kidney’s every minute
  40. 40. Circulation:  Renal arteries ◦ Interlobar arteries ◦ Arcuate arteries ◦ Interlobular arteries ◦ Afferent arteriole ◦ Glomerular capillaries ◦ Efferent arteriole ◦ Peritubular capillaries ◦ Interlobular veins ◦ Arcuate veins ◦ Interlobar veins ◦ Renal vein ◦
  41. 41. Physiology of the nephrons:  ◦ In glomerular filtration, the glomerulus filters water and certain dissolved substances from the plasma of blood. (Positive charge ions of sodium, potassium, calcium and magnesium. ◦ Both kidney’s filter about 45 gallons of blood plasma per day. ◦ Most fluid gets reabsorbed in the renal tubules and reenters the plasma.
  42. 42. Tubular reabsorption:  ◦ The majority of the reabsorption occurs in the proximal tubule. Active transport reabsorbs amino acids, glucose, creatinine, lactic acid, Uric acid, Citric acid, and Ascorbic acid. ◦ Osmosis reabsorbs water ◦ Chloride ions and other negatively charge ions are reabsorbed by electrochemical attraction.
  43. 43. Tubular Secretion:  ◦ The proximal convoluted tubule actively secretes penicillin, creatinine and histamine into the tubular fluid. ◦ It also secretes Hydrogen Ions (H+) thus helping in the regulation of body pH. ◦ Urine consist of water and solutes that the kidneys either eliminate or retain in the body in order to maintain homeostasis.
  44. 44. Renal Test:  ◦ There should be no RBC’s in the urine, but if the urine Dip is positive thinks always of Hemoglobinuria or Myoglobinuria. ◦ One common cause of Hemoglobinuria is red blood cells lysis. ◦ If you see RBC casts or crenated dysmorphic red blood cells indicate a renal origin and probable glomerulonephritis. ◦ If you see eosinophiluria think of drug induce interstitial nephritis.
  45. 45. There should very little proteins found in the  urine less than <150mg. ◦ Proteinuria is the best indicator of underlying renal pathology. ◦ More than 2.5-3.5 gm (or 40-50mg/kg/d) means significant glomerular pathology. ◦ A pathology called Myeloma often results in Bence- Jones proteinuria. The Bence Jones proteins are light chains which are not picked up on a urine dipstick.
  46. 46. Transient Proteinuria is common in people  during a febrile illness, also after strenuous exercise, and in patients with CHF and COPD. You should always check the urine when the situation as passed. Benign orthostatic proteinuria is a condition  in which the proteinuria reverts back to normal when the patient is supine.
  47. 47. Microalbuminuria is an indication of early  diabetic nephropathy this is not picked up on the urine dipstick. Later in the disease the condition turns into  nephrotic syndrome. Causes of false positive urine albumin on the  dipstick include a very alkaline urine with a pH >8, and a very concentrated urine.
  48. 48. GFR-Glomerular Filtration Rate, Urine to  plasma creatinine concentration X urine flow rate. Medicines that increase GFR are  cimetide, probenecid and trimethroprim sulfa TMP/SMX. Acetone and cefoxitin interfere with the test  for creatinine and may give falsely elevated results.
  49. 49. Creatinine is produce by muscle mass and the  breakdown of muscle tissue. Renal biopsy is used to diagnose causes of  acute renal failure, nephrotic syndrome, and glomerulonephritis.
  50. 50. Fluid and Electrolytes:  ◦ Normal Osmolatity is usually 282+or – 2 mosm/kg H2O. ◦ Osm = 2(Na) +Glucose/18+Bun/2.8
  51. 51. Urinary tract infection most common  pathogens: Gram-Negative bacteria ◦ Klebsiella ◦ Pseudomonas ◦ Proteus ◦ Enterobacter ◦ Escherichia coli ◦
  52. 52. Disorders of the Urinary System:  ◦ Kidneys stones known as calculi are composed of the precipitates of uric acid, magnesium or calcium phosphate, or calcium oxalate. ◦ Cystitis an inflammation of the urinary bladder ◦ Gout is a condition caused by high concentrations of uric acid in the plasma. Uric acid crystals. ◦ Glomerulonephritis is an inflammation of the kidneys where the filtration membrane within the renal capsule is infected with bacteria. (Following streptococcal sore throat infection). ◦ Renal failure ◦ Hematuria, oliguria or polyuria.