Renal

Cortex: outside area of kidney where glomeruli and 85% of the tubules reside.

Medulla: inside area of kidney where loops of henle and collecting ducts reside.

Pelvis: large collecting area of urine.

Hilum: entrance and exit for nerves, lymphatics, and blood vessels.

Nephron: functional unit of the kidneys.

  1. Glomerulus: tuft of capillaries where blood enters via the afferent arteriole and exits through the efferent arteriole.
  2. Bowman’s Capsule: filtrate enters here and consists of water, electrolytes, amino acids, glucose, and waste products.
  3. Proximal Convoluted Tubule: reabsorbs (solutes move from tubule to peritubular capillary) 2/3 of water and electrolytes, completes reabsorbs nutrients, vitamins, and small proteins.
  4. Loop of Henle: has descending and ascending limbs that concentrate urine.
  5. Distal Convoluted Tubule: sodium and water reabsorbed, potassium, hydrogen, and bicarbonate are secreted.

Glomerular Filtration Rate (GFR): how fast the kidneys are filtering. Can be primary display of kidney function.

  • blood volume is one of the most important regulators of GFR.
  • Normal GFR: 125 ml/min.
  • GFR is also reflected in creatinine levels.   * Creatinine: waste product made in muscles that is almost totally excreted in urine.     * if creatinine is increased in the blood, kidneys are not functioning as well.
Urinalysis
  1. Specific Gravity
  2. pH

       1. Normal pH of urine: 4.5-8.0.

  1. Glucose: should not see glucose in urine unless blood glucose is above 175 mg/dl.

       1. sign of hyperglycemia.

  1. Albuminuria: protein is normally absent from urine, when present it makes urine appear foamy.
  2. Pyuria: white blood cells in urine, indicates infection.
  3. Hematuria: blood in the urine, indicates inflammation or trauma to the area.
  4. Creatinine Clearance (24 hour): more specific assessment of GFR.
Hematology
  1. Blood Urea Nitrogen (BUN): end product of protein metabolism, less specific test of renal function, may be influenced by ingested protein and changes in fluid volume intake.
  2. Blood pH: acid-base balance, normal is 7.35-7.45.
  3. Hematocrit: low RBCs in the blood and may indicated decreased levels of erythropoietin.
  4. Albumin: levels of plasma proteins, decreased in failure.
  5. Electrolytes

       1. Potassium: indicates tubular ability to secrete, levels are increased in failure.

             1. abnormal levels of potassium predispose patients to cardiac arrhythmias.    2. Calcium: indicates kidney’s processing of the precursor to vitamin D, levels are decreased in failure.    3. Phosphate: indicates tubular ability to excrete phosphate, increased in failure.    4. Magnesium: indicates tubular ability to excrete magnesium, increased in failure.

Imaging and Histology
  1. Intravenous Pyelography (IVP): IV contrast administered, x-rays taken at regular intervals to evaluate filling and emptying of urinary tract.
  2. DEXA Scan: bone scan, tends to not be done with acute patients, assume the scan would be low.
  3. Biopsy

       1. Open: surgery.    2. Needle: percutaneous through lumbar area.    3. Cystoscopy: with scope via the bladder.

Urinary Tract Infections

  • Causes   * bladder retention   * obstruction to urine flow   * catheters   * immunosuppression   * impaired blood supply   * female anatomy

  • Urine cultures show greater than 100,000 organisms/ml.

  • Management   * UTI’s are treated with antibiotics and treating the underlying cause.   * hospitals have a push to remove catheters ASAP.

  • lower tract infections: called cystitis or urethritis.

  • upper tract infections: called pyelonephritis, in the renal pelvis and medulla.

  • Signs and Symptoms of UTI: low back, abdominal, or flank pain; dysuria, frequency, hematuria, pyuria, epithelial cells in urine; systemic signs are fever, malaise, nausea.

  • UTI’s in older adults tend to cause confusion. It tends to present as dementia that is rapid onset.

Acute Renal Failure

Acute kidney injury: sudden, severe decrease in renal function that is potentially reversible.

  1. associated with decreased GFR, oliguria, anuria, azotemia.

       1. Azotemia: urea in the blood.

  1. May require dialysis.
  2. Pre-existing conditions that increase risk of acute kidney injury:

       1. hypertension    2. atherosclerosis    3. diabetes mellitus    4. congestive heart failure    5. chronic liver pxs    6. pre-existing renal impairment

  1. Causes

       1. Prerenal Causes: diminished perfusion of kidney due to hypovolemia, decreased cardiac output, or thromboembolic obstruction of renal vasculature.    2. Postrenal Causes: obstruction of flow distal to kidney, causes increased pressure in bowman’s capsule and decreased GFR.    3. Intrarenal Causes: nephron damage, glomerulonephritis and acute tubular necrosis.

             1. acute tubular necrosis

                   1. most common cause of AKI.          2. often seen with nephrotoxic agents.

  1. Phases

       1. Oliguric Phase: 1-2 weeks, possible to not go through this phase.    2. Diuretic Phase: 2-10 days, inability to concentrate urine.    3. Recovery Phase: 8 days to 1 year later, lab values are normalizing.

  1. Labs with acute kidney injury:

       1. creatinine, BUN, and phosphorus increased.    2. calcium, pH, and hematocrit decreased.

Chronic Renal Disease

Primary renal disorders and systemic disorders may affect renal function and lead to ESRD.

  1. systemic causes: diabetes, hypertension, lupus, amyloidosis, scleroderma, and gout.
  2. Stages

       1. Stage 1: kidney damage with normal or increased GFR.

             1. GFR > 90       2. Diagnosis and treatment to slow the progression and do CVD risk reduction.    2. Stage 2: kidney damage with mild decrease in GFR.

             1. GFR = 60-89    3. Stage 3: moderate decrease in GFR.

             1. GFR = 30-59       2. evaluating and treating complications.    4. Stage 4: severe decrease in GFR.

             1. GFR = 15-29       2. preparation for kidney replacement therapy.    5. Stage 5: kidney failure.

             1. GFR < 15       2. need kidney replacement therapy.       3. signs and symptoms

                   1. volume overload = hypertension, JVD, lung crackles, peripheral edema.          2. carbohydrate intolerance (hyperglycemia)          3. changes in hormone synthesis and metabolism.          4. Renal Osteodystrophy: stimulation of osteoclasts by parathyroid hormone (osteoporosis, spontaneous fractures, avascular necrosis).

  1. Labs

       1. increased:

             1. creatinine       2. BUN       3. potassium       4. magnesium       5. phosphorus    2. decreased:

             1. calcium       2. pH       3. hematocrit       4. albumin

  1. Management of Chronic Kidney Disease

       1. Prevention

             1. maintain hydration       2. manage hypertension       3. prehydration for surgery or tests with nephrotoxic contrasts       4. maintain glucose levels       5. remove urinary catheters ASAP to prevent UTI.       6. volume replacement or vasopressors for hypotension.       7. monitor nephrotoxic drugs.    2. Early Detection    3. Nutrition

             1. renal failure causes profound catabolic state

                   1. calorie needs are increased by 50%.       2. restrictions: fluids, potassium, sodium, protein, phosphorus.       3. supplements: calcium, folic acid, vitamin D, B12, water-soluble vitamins, zinc.       4. tend to have significant weight loss.    4. Medical

             1. Pharmacologic

                   1. diuretics          2. synthetic EPO          3. calcium and vitamin D supplementation, phosphate binders          4. medication management       2. dialysis

                   1. hemodialysis

                         1. vascular access          2. peritoneal dialysis       3. transplantation

Physical Therapy Implications with Renal Disease

Monitor vital signs

  • impact of abnormal potassium on heart rate
  • impact of fluid on BP

Check lab values

  • hematocrit
  • potassium
  • calcium
  • DEXA scan

Signs and Symptoms to watch for:

  1. generalized fatigue
  2. decreased activity tolerance
  3. volume overload
  4. anemia or pulmonary compromise due to pulmonary edema
  5. pneumonia from immunosuppression
  6. pain
  7. muscle cramps

Bone Health: avoid torsion and encourage axial loading.

Fluid and Dietary Restrictions: may be strict on ins and outs.

\ \