Exam 3 patho: Renal Failure

Renal failure

When the kidneys fail to remove waste from the blood stream, and are unable to regulate fluid, electrolyte balance, and pH

Acute renal failure (ARF)

Rapid decline in kidney function

• few hrs to days

• Recoverable

Who is at risk for ARF?

• Elderly

  • bc they are at risk for hypervalemia (excess K+ in BS)

• Sepsis

  • this will take blood away from the kidneys and the BP will decrease and the kidneys won’t get the BF they need

• Sock

• Trauma

What is the result of acute renal failure?

Rapid decline in kidney function = inability to maintain fluid and electrolyte balance, and the ability to excrete it all

AKI manifestations

• Azotemia

• GFR decreases (glomerular filtration rate)

Azotemia

Accumulation of nitrogenous waste

3 types of renal failure, categorized by where the failure is occuring

• Prerenal failure

• Intrarenal failure

• Post Renal failure

Prerenal failure

Decreased blood flow to the kidneys due to hypovolemia, hypotension, decreased CO, and decreased kidney perfusion

In prerenal failure, GFR is _____ from decreased BF, BUT renal tissue is _______

GFR is decreased from decreased BF, BUT renal tissue is undamaged

Manifestiatons of prerenal failure

• Oliguria (Sharp decrease in urine output)

• Decreased secretion of Na+

  • means that the kidneys are trying to hold onto Na+, meaning that H2O will stay behind to try and increase BP

Intrarenal failure

Damage to the structure of the kidney, resulting in kidney failure

Causes of intrarenal failure

• Prolonged renal ischemia (ATN) (BP low for an extended period of time)

• Rhabdomyolysis (intratubular obstruction)

• Acute renal disease

• Exposure to nephrotoxic drugs (ATN)

• Acute tubular necrosis (most common)

Acute tubular necrosis (ATN)

Destruction of the tubular epithelial cells due to ischemia

Reversibility of Acute Tubular Necrosis

Reversible, but depends on the amount of injury the kidney has had overall and the ability of the body to rid itself of necrotic cells and create new tubular cells

In Acute Tubular Necrosis, does GFR improve with restoration of renal BF?

No

3 stages Acute Tubular Necrosis

1. Onset

   • lasting hrs to days

2. Maintenance

   • Decrease in GFR —> retention of metabolites and decrease in urine

   • Fluid retention observed

   • Prolonged oliguria

3. Recovery (1-3 wks)

   • Gradual increase in urine (diuresis)

   • Decrease in creatinine (indicates nephrons are recovering)

   • BUN, Cr, K+, and phosphorus may remain elevated, but will gradually decrease

   • Permanent damage to kidneys

How long does it take for a patient to recover from ATN?

3-12 months

Postrenal failure

obstruction of urine in ureter, bladder, or urethra

What is the most common cause of postrenal faiure?

Benign prostatic hyperplasia (BPH)

• Enlarged prostate

Acute vs Chronic Renal Failure GFR

• Acute RF has decreased GFR

• chronic has severely decreased GFR

Who is at risk for ATN?

• Those who already have renal insufficiency

• Elderly

• Diabetics

• Patients receiving certain meds

Chronic RF

Permanent loss of nephrons and significant reduction of GFR

Most common cause for chronic renal failure (CRF) (2)

• Diabetes

• HTN

How is staging of CRF determined?

GFR measurements

What can early diagnosis of renal failure do?

Preserve kidney function and delay CRF

What classifies someone with chronic kidney disease?

When patients are in stages 3-4 for 3+ months

Kidney failure is when GFR is less than ____ ml/min, and patients will need ____

• less than 15 ml/min

• Patients will need dialysis

Renal function tests for Chronic Renal Failure

• BUN and creatinine

• GFR

• Proteinuria

What will a proteinuria lab tell you when testing for CRF?

• LMW globulins

  • indicates tublulointestinal disease

• Albumin

  • Present due to chronic kidney disease, due to HTN or diabetes mellitus

Affects of CKD on the body (flow chart)

What is uremia? What are the symptoms?

• Organic waste in the blood

• Symptoms:

  • weakness

  • fatigue

  • nausea

  • apathy

Clinical manifestation of CRF (7)

• Fluid/electrolyte balance

• Acid/base balance

• Hyperphosphatemia and hypocalcemia

• Renal osteodystrophy

• Hematologic complications

• Cardiovascular

• Nitrogenous waste conditions

Fluid imbalance due to CRF

Early symptom is isosthenuria (polyuria)

• Urine is almost isotonic with plasma

Which electrolytes imbalanced due to CRF?

• Na+

• K+

Na+ imbalance due to CRF

• kidneys lose the ability to regulate Na+

• salt-wasting: body loses a lot of Na+

  • excreted in urine —> osmotic diuresis —> dehydration

• Others have Na+ retained

  • Results in HTN and HF

K+ imbalance due to CRF

• As the kidney starts to fail, the body tries to find other ways to get rid of excess K+ to maintain homeostasis

How can K+ be removed from body when kidney starts to fail? What happens when constipated?

• Removed through GI tract

• Constipation will result in decreased amounts of K+ being excreted from the body

Why does hyperkalemia occur?

Occurs when the output of K+ decreases (excretions from body)

Manifestations of hyperkalemia

• Weakness

• T-wave changes on an EKG

Acid-base imbalance results in metabolic acidosis, which results in:

• losing the ability to eliminate H+ ions (bc the tubules can’t move H+ back and forth within the filtrate very well)

• Unable to reabsorb bicarbonate (HCO3-)

• Ammonia cannot be produced (aids in buffering H+)

Hyperphosphatemia and hypocalcemia due to CRF

• Hyperphosphatemia: elevated PO4- in the BS; kidney’s inability to excrete

• Hypocalcemia: decreased Ca2+ in the BS

  • Due to the kidney’s inability to synthesize and activate vit D, resulting in Ca2+ binding to excess PO4-

What is the end result of increased phosphates and decreased calcium? Why?

Brittle bones because Ca2+ stored in bones is released to maintain serum Ca2+

Renal osterodystrophy due to CRF results from:

Occurs due to Secondary Paraythyroidism (chronic stimulation of PTH) and vitamin D deficiency

Causes of Renal Osteodystrophy

• Abnormal bone reabsorption

• Defective bone remodeling

Symptoms of Renal Osteodystrophy

• Softening of bones results in:

  • skeletal abnormailities

  • Bone pain

  • Fractures

• Muscle weakness

• Metastatic calcifications

Hematologic complications due to CRF

• Anemia

• Impaired platelet formation

• Hypercoagulability (altered clotting factors)

Why can anemia occur due to CRF?

This happens because:

• EPO production decreased

• Decreased half life of RBCs

• BM suppression from uremia

• Iron deficiency from diet and restriction and anorexia

How are platelets impaired?

Defective platelet aggregation and impaired adhesions to endothelium

Cardiovascular issues due to CRF

• Hypertension And diabetes mellitus

• Dyslipidemia (due to uremia)

• Endothelial cell dysfunction and Ca2+ deposits

• Pericarditis

What is the most common cause of death among those with kidney disease?

Cardiovascular issues

What is the endothelial cell dysfunction and Ca2+ deposits due to CRF?

• Loss of vessel elasticity and vascular calcifications

• Increased risk of ischemic heart disease, LVH, CHF, stroke, and PVD

Pericarditis due to CRF

• Occurs in 20% of chronic dialysis patients

• Caused by inflammatory process and uremic toxins

• Mild to severe chest pain and pericardial friction rub

Nitrogenous waste conditions due to CRF

• Neuromuscular

• GI

• Infection and immune

• Sexual

• Skin

Neuromuscular disorders associated with nitrogenous waste of CRF

• PNS and CNS dysfunctions

  • Neuropathies

  • Restless leg syndrome

• Uremic encephalopathy

• Motor dysfunction

Neuropathies

Related to demylinization of nerve fibers, likely due to renic-toxins that the body cannot get rid of

Restless leg syndrome

Creeping/prickling sensation at rest in legs

Uremic encephalopathy due to neuromuscular disorders of CRF

• When the uremia affect the brain tissue

• Patients less alert, impaired judgement, and have memory loss

• Can get to the point where it causes seizures and coma

Motor dysfunction due to neuromuscular disorders of CRF

• From muscle weakness

• If you have peripheral nerve damage patients might have burning to the feet

GI dysfunction associated with nitrogenous waste of CRF

• Loss of appetite due to nausea bc of uremia:

  • Anorexia

  • Nausea and vomiting

• Metallic taste

• Uremic factor

• GI bleeding and ulceration

Infection and immune disorders associated with nitrogenous waste of CRF

• Suppression from urea & waste

• Impaired skin & mucosal barriers

• Malnutrition contributes to immunosuppression

Skin issues associated with nitrogenous waste of CRF

• Dry skin

• Pruritus

• Uremic frost

Sexual issues associated with nitrogenous waste of CRF

Multifactual

• has a lot to do with urinary toxins and neuropathy and some medications patients are on

Disorders of Drug Elimination (4)

• Phosphate binding drugs

• Drugs may contain unwanted (Nitrogen, K, Na, Mg)

• Decreased Elimination & Metabolism

• Low plasma proteins levels

  • Many drugs bind with plasma proteins

  • Unbound drugs can be harmful

Phosphate binding drugs

can interfere with absorption of other drugs

Diet for those with CRF

• Protein — decrease (high protein can lead to high BUN)

• Na+ — decrease

• Fluid — decrease to 500-800 mL/day

• K+ — increase when GFR drops significantly

Why would someone need to decrease their sodium intake if they have CRD?

• Glomerular origin causes Na+ retention

• Tubular dysfunction causes salt wasting

Where is phosphorous found in food? (3) What is the impact on poor patients?

Found in processed foods, instant products, and beverages

• this makes it harder for POOR patients to adhere to decreased phosphorous

Where is K+ found in food? (4)

• Salt substitutes

• Fruits

• Fruit juices

• Chocolate

Medical management for Chronic Renal Failure

• Peritoneal dialysis

• Hemodialysis

• Kidney transplant

Peritoneal dialysis

Catheter is inserted into abdomen and it uses the lining of your abdomen to filter blood inside the body

• works very well but need to be dedicated

Hemodialysis

circulating the blood outside the body through a machine that filters out toxins and returns the cleansed blood to the patient

• needs needles in arms 3x per week