Kidney Anatomy and Acute Renal Failure

• Acute renal failure is also known as acute kidney injury
• Acute kidney injury is the sudden loss of kidney function
• Acute kidney injury often is caused by severe infections, kidney infections, or dehydration
• Acute kidney injury is typically reversible with prompt treatment

Kidney Functions and Related Anatomy

• Kidneys maintain fluid and electrolyte balance
• The kidneys regulate blood pressure
• The kidneys filter out waste products
• Kidneys produce hormones involved in red blood cell production and bone health
• Kidneys are bean-shaped
• Kidneys are located in the retroperitoneal space on each side of the spine, in the upper abdominal cavity
• Kidneys have an outer cortex, inner medulla, and approximately one million nephrons
• Nephrons are the functional units of the kidney

Micturition

• Micturition is the process of voiding
• With micturition the bladder fills and stretches activating stretch receptors that signals reflex
• During micturition the detrusor muscle contracts and the external urethral muscle consciously relaxes
• Infants have no control and urinate about 8-10 times per day
• As infants age and the neuromuscular system matures they learn to control urethra muscles
• Older adults experience kidneys age, muscles age, urgency, frequency increases, and loss of bladder elasticity and tone
• Bladder elasticity and tone results in nocturia and incomplete emptying

Glomerular Filtration Rate

• Kidneys receive approximately 1/5 of cardiac output
• Glomerular filtration rate (GFR) is renal blood filtered per unit of time and is directly related to renal perfusion
• Decreased renal perfusion decreases GFR
• GFR reduces with aging
• GFR is the indicator of kidney function (filtration)
• Nephron is the basic functional unit of the kidney and assists with filtration, reabsorption, and urine formation

Nephron Structure and Function

• Nephron consists of key components that work together to process filtered fluid and produce urine
• Glomerular capillaries are specialized capillaries located in the renal corpuscle.
• Glomerular Capillaries have a unique structure with high hydrostatic pressure, favoring filtration
• Filtrate, which contains water, electrolytes, and waste products, moves from the glomerulus into Bowman's capsule
• Proximal tubule follows Bowman's capsule
• The proximal tubule reabsorbs the majority of the filtrate back into the bloodstream
• Reabsorption retrieves important substances such as glucose, amino acids, water, and electrolytes
• The loop of Henle is U-shaped and located between proximal and distal tubules
• The loop of Henle concentrates the filtered fluid and urea also enters
• Distal tubule follows the loop of Henle and reabsorbs water and sodium
• Reabsorption in the distal tubule is regulated by aldosterone
• Collecting ducts perform final adjustments in urine concentration
• Antidiuretic hormone (ADH), or vasopressin, facilitates additional water reabsorption in the collecting ducts
• Urine is the end product, the remaining filtrate after reabsorption and concentration

Substances that are Filtered, Reabsorbed, and Secreted

• The kidney filters waste products, excess water, electrolytes, from the blood to form urine
• Filtration occurs in the glomerulus, a capillary tuft within each nephron
• Reabsorption reclaims essential substances like glucose, water, electrolytes, and amino acids
• Reabsorption occurs from the renal tubules back into the bloodstream
• The renal threshold to reabsorb glucose is a blood glucose(BG) of 180 mg/dL and is responsibility for insulin processes
• Glucose presence in the urine after this
• Reabsorption occurs primarily in the proximal convoluted tubule and other segments of the nephron
• Secretion moves substances like drugs, toxins, and hydrogen ions, from the blood into the renal tubules for excretion
• Secretion mainly occurs in the distal convoluted tubule and the collecting ducts

Body-Balancing Renal Functions

• Regulation of Fluid and Electrolyte Balance: Kidneys maintains electrolyte and fluid balance
• Acid-Base Balance: Kidneys regulate acid base balance by excreting hydrogen ions and reabsorbing bicarbonate ions
• Acid-Base Balance assists in a slightly alkaline pH
• Blood Pressure Regulation: Kidneys produce and release the enzyme renin
• Renin initiates the renin-angiotensin-aldosterone system to constrict blood vessels and increase sodium and water reabsorption
• Blood Pressure Regulation leads to elevated blood pressure.
• Vitamin D Production and Activation: Kidneys activate vitamin D which allows calcium absorption
• Kidney disease makes Vitamin D Production and Activation very important to assess
• Hormone Production: Kidneys produce erythropoietin (EPO) and calcitriol (active form of vitamin D)
• EPO and calcitriol are active forms of vitamin D and have key functions in red blood cell production and calcium metabolism
• EPO: Specialized kidney cells sense low oxygen levels (hypoxia)

Erythropoietin

• Erythropoietin (EPO) increases production and release
• Erythropoietin (EPO) travels to the bone marrow and binds to surface receptors on hematopoietic stem cells
• This binding stimulates proliferation and differentiation of stem cells into mature red blood cells
• Erythropoietin (EPO) production and release is regulated by oxygen levels, anemia, and hormonal signals

Renal Diagnostic Testing and Indicators

• Blood Creatinine indicates muscle and protein breakdown
• With a loss of at least 50% of kidney function, blood creatinine will increase
• Blood creatinine is the best indicator of damage
• Blood urea nitrogen (BUN) indicates the breakdown of protein in the liver (bi-product is nitrogen)
• Blood urea nitrogen (BUN) is affected by dehydration, infection, chemotherapy, and steroid use
• Blood urea nitrogen (BUN) elevation shows kidney disease
• However liver failure limits urea production and causes a decrease in blood urea nitrogen (BUN) for liver and kidney failure
• Glomerular filtration rate (GFR) is best for glomerular function and filtration
• Estimated Glomerular filtration rate (eGFR) is calculated from the serum creatinine and utilizes race, age, and gender variables
• Urinalysis is used to identify urologic disorders
• Urinalysis is also used for color, clarity, concentration/dilution, specific gravity, acidity/alkalinity, drug metabolites, glucose,ketones, protein, leukocytes, nitrites, and bacteria
• A 24-hour urine collection measures creatinine, urea nitrogen, sodium, chloride, calcium, catecholamines, and proteins
• Collection of urine helps also to measure the glomerular filtration rate and collection requires discard of the first voided specimen
• Urine must be refrigerated or on ice
• KUB (Kidneys, Ureters, Bladder X-Ray) is used to see the shape, size, and position of the kidneys, ureters, and bladder
• During an x-ray of the kidneys, ureters, and bladder, contrast may used through the urethra for better visualization and checking for reflux from the bladder back into the kidney
• Also used are X-ray, CT, MRI, Ultrasound, Kidney biopsy, Cystscopy video, and Renal scan of blood flow

Kidney Consequences and Issues

Insufficient filtration: Waste product buildup

• Kidney Dysfunction Consequences : Urine not concentrated
• Kidney Dysfunction Consequences : Toxin buildup leading to the destruction of blood cells
• Kidney Dysfunction Consequences : Neurological issues, Confusion, stupor, encephalopathy
• Kidney Dysfunction Consequences : Excess renin secreted, raising BP
• Kidney Dysfunction Consequences : Decreased erythropoietin, decreasing RBC's
• Kidney Dysfunction Consequences : Acid-base balance not maintained
• Kidney Dysfunction Consequences : Excess K+ not secreted
• Kidney Dysfunction Consequences: Decreased vitamin D and decreased Ca++ absorption

Kidney Failure Symptoms

• Decreased urine output
• Edema (swelling) in the legs, ankles, or face
• Fatigue and weakness
• Shortness of breath
• Nausea and vomiting
• Changes in appetite and weight loss
• Difficulty concentrating and mental confusion
• Electrolyte imbalances show a high potassium level, low Ca+ absorption
• Pyelonephritis is the infection and inflammation of the kidney pelvis, calyces, and medulla.
• Pyelonephritis: Infection usually begins in the lower urinary tract and the organism works its way upward into the kidney which is known as an infection of the upper urinary tract/kidney
• The most common organism is E. coli and the infection impairs filtration, reabsorption, and secretion
• Repeated infections create scarring of the tissue
• Antibiotic treatment for UTI that includes Ciprofloxacin carries a risk of tendon rupture
• Fluoroquinolone antibiotics are associate with an increased risk of tendon rupture; instruct the client to report any tendon swelling or inflammation immediately
• Pyelonephritis is most often seen in females ages 20-30, Kidney stones (frequent) increase risk, Reflux when backward flow of urine from the bladder into the kidney and pregnancy increases risk, Males over 65 years increase risk due to prostatitis and hypertrophy of the prostate
• Pyelonephritis includes chills, abdominal pain (colicky), nausea, malaise/fatigue, urinary tract infection symptoms, CVA tenderness often costovertebral angle tenderness, flank and back pain, fever, tachycardia, tachypnea, hypertension, and vomiting

Kidney Stones

• The cause for kidney stones is unknown but most are composed of calcium phosphate or calcium oxalate and occurs more often in males than females
• Reoccurrence risk increase in males if first occurs before age 25
• Uretero is in the ureter
• Pyleo is the kidney pelvis
• Nephro is the kidney
• Symptoms include severe back/flank pain (renal colic) that intensifies as the calculus moves through the ureter and pain goes into the groin.
• Calculus movement may cause radiation to the abdomen, scrotum, testes, and vulva when the calculi has moved to the ureter or bladder. Red of rusty-colored urine will be noticed Urinary frequency will increase
• Symptoms of calculus include Diaphoresis, pallor, nausea/vomiting, tachycardia, tachypnea, and blood pressure changes
• An obstruction may occur if the calculi can become stuck preventing flow from the kidney to the bladder and/or urethra which is an emergency requiring surgery to prevent irreversible kidney damage
• Nephrolithiasis = formation of stone in kidney
• Ureterolithiasis = formation of stone in ureter
• Treatment includes IV Fluids and flushing of the kidneys
• Opioids and NSAIDS are given to manage any pain along with bladder spasm medication
• Tamsulosin (Flomax) is administered to allow the muscles of the prostate and bladder increasing flow, antibiotics (gentamicin and cephalexin) may be administered
• Strain the urine and increase oral fluid intake to > 3 liters/day
• Lithotripsy and Uterocystoscopic surgery is administered Surgical stent placement is administered to dilates the ureter and allow passage of calculus.
• Large calculus may require another surgery
• Renal calculus can cause severe pain which will cause nausea and vomiting

Diagnosing and Care of Kidney Issues

• Nursing assessment and treatment for kidney issues include:
  • Pain
  • Urinalysis to consider straining urine
  • BUN
  • Creatinine (blood and urine) levels
  • GFR and eGFR
  • WBC Normal Values to Know:
  • Normal Values to Know: BUN 10-20 mg/dL
  • Normal Values to Know: Creatinine serum 0.5 – 1.3 mg/dL and is related to gender and age
  • Normal Values to Know: Hemoglobin 12-18 g/dL related to gender
  • Normal Values to Know: Potassium 3.5-5.0 mEq/L Clinical Manifestations of Kidney Dysfunction: Abdominal Pain and Confusion: Kidney dysfunction can present with abdominal pain, which can be due to renal calculi or kidney function.

Costovertebral Angle (CVA) Tenderness: Tenderness can show kidney inflammation or infection.

• Hematuria refers to blood presence in the urine and also to renal calculi (kidney stones) or urinary tract infection
• Proteinuria is urine proteins and an early sign of renal damage or kidney disease
• Tea-Colored Urine: Tea-colored urine and high bilirubin, can occur in conditions affecting liver function or obstructive disorders of the biliary system.
• Blood Urea Nitrogen (BUN): BUN that is high is azotemia, indicates impaired renal function, and influenced by multiple diet factors, also used as indicator of improvement of kidney function with other markers
• Serum Creatinine is creatinine broken down from breakdown product of muscle that can also use as an indicator of kidney
  • Increased serum creatinine levels also reflect decreasing GFR and impaired kidney function. Nursing Implications: is conducting assessments of abdominal pain, urinary changes, and CVA tenderness
• Nursing Implications incluse monitoring blood value markers that reflect kidney heath
• Nursing Implications incluse collaboration with team on treatment, educating patient's on hydration, diet, and meds

Types of Renal Injuries

Prerenal is marked decrease in renal blood flow also known as decreased blood flow and perfusion to the kidney, resulting in hypovolemic shock Intrarenal is the kidney damage and injuries to the kidney itself Postrenal is the obstruction of urine outflow from the kidneys.

• Blood flow is a factor to the GFR rate Hypovolemia, reduces renal perfusion, results from vomiting diarrhea, excessive sweating, or hemorrhage. Heart failure, has issues pumping blood effectively with cardiac output reduced that limits filtration

Shock and Kidney Failure Dynamics

Shock is life threatening with limited flood and oxygen delivery to the kidneys Damage to Kidney (Intrarenal) is with Damage to the tissue itself:

• Untreated HTN and Uncontrolled Diabetes cause issues
• Trauma such as blunt force to the kidneys, disrupts blood supply and impairs function
• Pyelonephritis and Autoimmune Conditions like infections and lupus
• Nephrotoxic Drugs are NSAIDs, ACE inhibitors, angiotensin receptor blockers (ARBs), statins, and some antibiotics all impair Kidney function

Postrenal

Refers to obstructive conditions that prevent or hinder the normal flow of urine from the kidneys like with kidney stones and prostate issues

• AKI refers to an abrupt insult to the kidney and is often restored
• Common signs of AKI include azotemia and creatinine/fluid retention
• PReenal AKI common because of kidney death
• Causes range from renal ischemia, low blood volume, to hemorrhages. Intrinsic AKI refers to kidney damage that effects the renal tissues
• Medications such as NSAIDs can nephrotoxic. or lead to nephron damage
• Conditions of excess hemoglobin, from muscle contribute to intrinsic AKI

Postrenal AKI occurs from obstructrive out of the kidney

• Caused by kidney stones and prostate issues
• Obstruction causes backups fluid to the kidney
• Stagnant urine causes risk and nephron toxic issues

Kidney Tubular Necrosis

Necrosis is ischemia damages kidney tissues due to a blocking effect, The tubules Treatment for AKI must maintain a correct balance of fluids/electrolytes Treatment for an AKI underlying issues

• Prompt interventions such as fixing meds
• Use bicarbonate to keep the acid in balance but with cases its renal treatment

Phases of the Kidney

Initial Phase Second Maintenance Phase where oliguria is an important concept (also loss of electrolytes The Recovery Phase occurs when healthy items resumes

Kidney Treatment Dialysis and Shunts

Treatment for kidneys with function issues Hemodialysis: is a machine assisted process

• AV Shunt (arteriovenous) – you are auscultating a bruit (turbulent flow), palpating "feel” a thrill, verifying pulses distal to the shunt, and circulation).
• Can cause loss of weight and a rapid cerebral edema Peritoneal Dialysis is a body treatment
• Inflow and outflow should be similar, the color yellow, watch the site!! Maintain clean environment and prevent infection

Post Complications

• Disequilibrium
• Shunting
• Severe Hemmorrhae

Post-Op Kidney Care

• High BP and respiration issue indicates bad signs
• Monitor blood pressure, apply medications if necessary
• Patient need to promote chest expansion
• Assess breathing circulation, blood pressure etc to analyze for abnormalities
• After that, keep the patient supported in their current health needs

Learn about acute kidney injury causes, symptoms, and treatments. Explore kidney functions like fluid balance, blood pressure regulation, and waste filtration. Understand kidney anatomy including the cortex, medulla, and nephrons.