GU/Renal Flashcards
Rhabdomyolysis Overview
S/Sx
- acute onset of muscle pain (not r/t physical exertion)
- muscle weakness
- dark urine (myoglobinuria) d/t myoglobins released from damaged muscle → reddish-brown or tea-colored urine; damages kidney → AKF (common complication of rhabdo)
- muscle tenderness & swelling may be seen → r/o compartment syndrome
Labs
- Serum creatine kinase markedly ↑ (5x normal)
- Blood chemistry abnormalities
- ↑ aldolase, LDH
- electrolyte abnormalities
- DIC possible complication
Ask pt if hx of severe exercise, crush injury, high fever, or high-dose statin use
REFER TO ED!
Acute Pyelonephritis Overview
S/Sx
- acute onset of high fever
- chills,
- N/V
- dysuria
- frequent urination
- unilateral flank pain described as “deep ache”
- hx of URI
Indications for hospitalization:
- inability to maintain oral hydration
- persistently high fever >101º/38.4º
- toxic appearance
- immune compromise
- suspicion of sepsis
- noncompliance to treatment
Acute Kidney Injury (Acute Renal Failure) Overview
S/Sx
- abrupt onset of oliguria
- edema
- weight gain (fluid retention)
- lethargy
- nausea
- loss of appetite
characterized by rapid ↓ in renal function and ↑ serum creatinine
During early stages, serum creatinine and eGFR may not accurately reflect true renal function
Most causes of AKI; acute decline of GFR are usually reversible when offending substance is stopped
Most common causes:
- drug-induced AKI (e.g., aminoglycosides, contrast agents, NSAIDs, ACEi, and protease inhibitors)
** Serum potassium should be monitored upon initiation of ACEi or ARB if pt has kidney disease; potassium levels may initially rise and then tape off in 2-3 months; continued monitoring of serum potassium is recommended
Bladder Cancer Overview
S/Sx
- elderly male (median age at dx: 73 years) who smokes w/ painless hematuria (can be microscopy or gross [pink- to reddish-color urine])
- some pts only notice problem after see blood-tinged stain on underwear (males, menopausal females)
- hematuria may only appear at end of voiding
may have irritative voiding sx, NOT related to UTI:
* dysuria
* frequent urination
* nocturia
Dx:
- Order UA, urine C&S, and urine cytology
Those w/ advanced disease may c/o lower abdominal or pelvic pain, perineal pain, low-back pain, or bone pain
Normal Findings: Kidneys
1. Location
2. Function
- Located on retroperitoneal area
- R kidney is lower than L kidney d/t liver displacement
- Basic functional units of kidney: nephrons which contain glomeruli - regulates body’s electrolytes and fluids (affects BP)
- water is reabsorbed back into body by action of antidiuretic hormone and aldosterone
- kidneys excrete water-soluble waste products of metabolism (e.g., creatinine, urea, uric acid) into urine
- secrete several hormones (e.g., erythropoietin-RBC production, renin, and bradykinin-BP, prostaglandins-renal perfusion, and calcitriol/vitamin D3-bone)
- average daily urine output is 1,500 mL
- regulates body’s electrolytes and fluids (affects BP)
Oliguria
urinary output of <400 mL/day (adults)
Lab testing: Serum Creatinine, M vs F
end product of creatinine metabolism, which comes mostly from muscle
- may be falsely ↓ in people w/ low muscle volume (older adults)
** Elevated values seen in pts w/ kidney damage/failure ,use of nephrotoxic drugs, etc
M: 0.7-1.3 mg/dL
F: 0.6-1.1 mg/dL
Factors affecting serum creatinine:
- gender (M > F)
- race (African Americans have more muscle mass)
- muscle mass
When renal function ↓, creatinine level will ↑
** Serum creatinine is a better measure of renal function than BUN or BUN:Cr ratio; but eGFR** is considered the best measure of renal function in primary care
Lab Testing: Estimated Glomerular Filtration Rate
Normal: eGFR >90 mL/min
CKD: eGFR <60 mL/min for at least 3+ months
*Best test to measure kidney function; used to determine chronic kidney ds stages
Calculated by using serum creatinine, age, and gender (with adjustment for those of African American descent)
Estimation Equations, used to calculate eGFR:
- Modification of Diet in Renal Disease (MDRD)
- Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)
- Cockcroft-Fault equation
GFR: amount of fluid filtered by the glomerulus within a certain unit of time; the more damaged the kidneys, the ↓ the eGFR; affected by age (↓ w/ age), sex (M have more muscle mass), and body size
- African Americans’ eGFR values are higher than other races
- Some pts w/ underlying kidney ds may have a normal eGFR
- eGFR is LESS reliable in these cases: pregnancy, muscle wasting, elderly, and LE amputees
Chronic Kidney Disease Stages
1. Stage 1
2. Stage 2
3. Stage 3a
4. Stage 3b
5. Stage 4
6. Stage 5
- > 90 mL/min → Kidney damage w/ normal kidney fx
- 89-60 mL/min → Mild loss of kidney fx
- 59-45 mL/min → Mild-to-mod loss of kidney fx
- 44-30 mL/min → Mod-to-severe loss of kidney fx
- 29-15 mL/min → Severe loss of kidney fx
- <15 mL/min → Kidney failure
Blood Urea Nitrogen (BUN)
- Definition
- What does an elevated BUN mean?
- Causes of elevated BUN? Low BUN?
- Mortality?
- Which lab should you check if abnormal BUN level?
- Liver breaks down amino acids into ammonia → converts it into urea
- BUN = measure of kidneys’ ability to excrete urea (waste product of protein metabolism)
If kidneys are damaged or renal blood flow is ↓, urea level ↑
- NOT as sensitive as serum creatinine or eGFr
High BUN may be caused by:
- acute kidney failure (lowers GFR)
- high-protein diet
- hemolysis
- CHF
- drugs
- Among HF, lower GFR w/ higher BUN = higher mortality; in ICU, ↑ BUN is independently associated w/ higher mortality
Low BUN causes:
- liver damage/disease
- If abnormal BUN level, check eGFR. If eGFR is normal, renal fx is normal
BUN-to-Creatinine Ratio
- ↓ in blood flow of kidneys will ↑ BUN:Cr ration
- used to help evaluate dehydration, hypovolemia, and AKF
- useful for classifying type of failure (renal, infrarenal, or postrenal)
Urinalysis (with Microscopic Exam)
- 3 components of a complete UA
A complete UA consists of 3 components:
- gross evaluation
- dipstick analysis
- microscopic exam of urine sediment
UA: Epithelial Cells
- Large amount of squamous epithelial cells = contamination
- A few epithelial cells = normal
Squamous epithelial cells are associated w/ external urethra and transitional epithelial cells w/ the bladder
UA: Leukocytes
Normal WBC in urine: ≤2-5 WBCs/hpf (high-power field)
- Called leukocyte esterase test w/ urine dipstick strips
- Presence of leukocyte sin urine (pyuria) is ALWAYS abnormal in males →infection
- UA is more sensitive test for infection in males than females
UA: Urine for C&S
≥ 10^5 colony-forming units (CFU)/mL is one dominant bacteria (usually E. coli)
* E. coli = Gram- Enterobacteriaceae
- If multiple bacteria are present = contaminated
- Lower vales = bacteriuria
UA: Reb Blood Cells
- Microscopic vs gross hematuria
- Few RBCs (<3 cells) = normal
- Microscopic hematuria refers to RBCs that are visible only by microscopy
- Gross hematuria = see blood in urine
- Color ranges from pink, red, to cola, or brown
- source of bleeding may come from urethra (urethritis), bladder (cystitis, bladder cancer), or kidneys (kidney stones, pyelonephritis, polycystic kidneys, cancer)
- can be contaminated by menses, vaginal discharge, semen, hemorrhoids, rectal bleeding
UA: Protein
- Indicates kidney damage if persistent (CKD)
Next step: order serum creatinine and eGFR and send midstream urine for microscopic exam
- If normal microscopic exam for urine sediment and normal kidney fx → isolated proteinuria
-Transient proteinuria is common, esp in age ≤18 years (8-12%) and among young adults (4%)
Benign causes:
- fever
- intense physical activity
- acute illness
- dehydration
- emotional stress
- May be present in acute pyelonephritis (resolves after tx) → recheck urine after tx
- Urine dipsticks detect only albumin
- False-positive results w/ urinary dipstick testing may be seen w/ alkaline urine (pH >7.5), if dipstick is immersed too long, highly concentrated urine, gross hematuria, presence of semen, or vaginal secretions
- To quantify proteinuria, order 24-hour urine for protein-to-creatinine ratio (UPr/Cr)
UA: Nitrates
- Positive → highly indicative of UTI
- Due to breakdown of urea into nitrate by bacteria
UA: Casts
- Casts are shaped like cylinders d/t forming in the renal tubules
Hyaline casts: nonspecific; can be seen in small volumes in concentrated urine or w/ diuretic therapy
WBC casts: seen w/ infections (pyelonephritis) or inflammation (interstitial nephritis)
RBC casts: Caused by microscopic bleeding in glomeruli; suspect glomerulonephritis (accompanied by edema, weight gain, dark cola-colored urine, or HTN)
UA: pH
4.6-8.0 (reference range)
- useful in evaluation of kidney stones and infections
- citrus and low-carbohydrate diet are associated w/ lower acidity and high-protein is associated w/ higher acidity
Hematuria
1. Definition/Etiology
2. Clinical Presentation
3. Lab/Diagnostics
4. Treatment Plan
- 2 types: microscopic vs gross
- either transient or persistent
- blood can come from urethra (urethritis), bladder (cystitis), bladder cancer), prostate (prostatitis), or kidneys (pyelonephritis, polycystic kidneys, cancer)
- microscopic → only revealed by microscopic UA (presence of ≥3 RBCs/hpf)
- Gross (or visible) hematuria if color is pink, red, or brown or blood clot present → next step, look for source of blood
- If infection suspected → urine for C&S
- New onset of dark reddish-brown urine, edema, proteinuria, fatigue, and ↓ urine output after a recent strep through, scarlet fever, or impetigo → possible poststreptococcal glomerulonephritis (an immune reaction from infection); can occur 10 days after infection and up to 3 weeks after; rare complication; more common in children
- If malignancy suspected → urine for cytology and refer to specialist
- RF: >50 years, male, smoker, and gross hematuria
- Red urine NOT d/t bleeding can be caused by some meds (e.g., rifampin, phenytoin), and ingestion of certain foods (e.g., beets, rhubarb, senna, food dyes)
- Causes & treatment:
- Female w/ hx of vigorous sexual activity/exercise → stop exercise and repeat 4-6 weeks
- Menses → repeat UA ~1wk after last day of menses; repeat UA w/ microscopic exam
- If infection (e.g., urethritis, cystitis, pyelonephritis) is suspected, UA will show WBC (w/ or w/out nitrates) + associated s/sx (dysuria, frequency, urgency, nocturia) → order UA w/ urine for C&S
- Persistent unexplained microscopic hematuria that does not resolve → refer to nephrologist
Proteinuria
1. Definition/Etiology
2. Types of proteinuria
3. Urine dipstick
4. Benign causes
5. Serious causes
- excretion of >150 mg/day of protein
- If persistent, find the cause!
GOLD STANDARD: 24-hour urine for protein
- glomerular
- tubular
- overflow
- postrenal
- glomerular
- Urine dipstick cannot detect low levels of albumin
- pts w/ moderately ↑ albuminuria (previously known as microalbuminuria) may not be detected unless urine is concentrated - fever
- intense physical activity
- acute illness
- dehydration
- emotional dress
- drugs
- fever
- sign of damaged kidneys
- diabetic nephropathy
- hypertensive nephropathy
- polycystic kidney disease
- sarcoidosis
- lupus
- rhabdomyolysis
- preeclampsia
- eclampsia
- sign of damaged kidneys
Nephrotic Drugs
- ACE inhibitors or ARBs
- Acyclovir
- Allopurinol (Zyloprim)
- Aminoglycosides (vancomycin)
- Antiretrovirals (adefovir, cidofovir, tenofovir, indinavir)
- Beta-lactams (penicillins, cephalosporins)
- Chemotherapeutics
- Contrast dyes
- Diuretics (thiazides, loop, triamterene)
- Drugs of abuse (cocaine, heroin, ketamine, amphetamines)
- Lithium
- NSAIDs and analgesics (acetaminophen)
- Proton-pump inhibitors (lansoprazole, omeprazole, pantoprazole)
- Quinolones (ciprofloxacin)
- Sulfanomides
** Pts w/ preexisting kidney disease and/or diabetes are at higher risk of kidney damage from contrast media; CT, MRI, and angiogram contrast media may damage kidneys (2%) or cause nephrogenic systemic fibrosis
Asymptomatic Bacteriuria
1. Definition/Etiology
2. Screening for/Treating Asymptomatic Bacteriuria
- presence of one or more species of bacteria growing in urine (≥10^5 CFU/mL) in absence of UTI symptoms, irrespective of presence of pyuria
- Healthy premenopausal (nonpregnant) and health postmenopausal women
- Older community-dwelling persons who are functionally impaired
- older persons who are residents of long-term care facilities (nursing homes)
- Diabetics
- Spinal cord injury
- long-term indwelling catheters
- infants and children
- Healthy premenopausal (nonpregnant) and health postmenopausal women
Bacteruric pt w/ fever → symptomatic bacteriuria w/ systemic signs of potentially severe infection (sepsis); treat w/ broad-spectrum antimicrobial therapy → Refer to hospital
Pregnant women: screening and treating for ASB is recommended (2-7% have ASB)
- higher risk (30%) for pyelonephritis
- Tx w/ antibiotics for 4-7 days
- Nitrofurantoin and beta-lactams (ampicillin, cephalexin) preferred
* Avoid nitrofurantoin near term d/t risk of fetal hyperbilirubinemia
