Genitourinary Renal System

A comprehensive set of practice flashcards covering AKI/CKD concepts, urinalysis interpretation, infectious diseases of the kidney and urinary tract, nephrolithiasis, and related pathophysiology and management based on the provided notes.

What is Acute Kidney Injury (AKI) and what is its typical prognosis when the offending substance is stopped?

AKI is an abrupt decline in GFR with decreased renal function; most cases are reversible if the offending agent is discontinued.

Name common drug classes that can cause AKI.

Aminoglycosides, contrast agents, NSAIDs, ACE inhibitors, and protease inhibitors.

What are the KDIGO criteria for diagnosing AKI?

Increase in serum creatinine by ≥0.3 mg/dL within 48 hours or an increase ≥1.5 times baseline; urine output <0.5 mL/kg/hr for 6 hours.

Differentiate prerenal AKI from intrinsic (ATN) and postrenal AKI.

Prerenal: hypoperfusion of kidneys; Intrinsic (ATN): damage to renal parenchyma; Postrenal: obstruction to urine flow.

What are key aspects of initial management in AKI?

Eliminate nephrotoxic insults, treat hypovolemia, correct electrolyte disturbances and acidosis, provide nutrition, and refer to ED/nephrology as needed.

What are the classic symptoms of acute pyelonephritis?

High fever with chills, nausea/vomiting, dysuria, frequency, and unilateral flank pain.

Which patients with pyelonephritis typically require hospitalization?

Inability to maintain oral hydration, persistently high fever, toxic appearance, immune compromise, suspicion of sepsis, or noncompliance.

Most common organisms causing acute pyelonephritis?

Gram-negative Enterobacteriaceae, especially Escherichia coli; also Proteus and Klebsiella.

What is the classic presentation of bladder cancer in the elderly smoker?

Painless hematuria (microscopic or gross), possibly with irritative voiding symptoms.

What is the recommended workup for suspected bladder cancer?

Urinalysis, urine culture and sensitivity, and urine cytology.

What is the classic triad and key lab finding in rhabdomyolysis?

Muscle pain, muscle weakness, dark urine; markedly elevated creatine kinase (often ≥5x normal).

What history factors raise suspicion for rhabdomyolysis?

Severe exertion, crush injuries, very high fever, or high-dose statin use.

Where are the kidneys located and what is their basic functional unit?

Retroperitoneal; nephrons containing glomeruli are the basic functional units.

What kidneys-related hormones and factors influence BP and bone health?

Erythropoietin, renin, bradykinin, prostaglandins, and calcitriol (vitamin D3).

What is the average daily urine output in a healthy adult?

About 1,500 mL.

Which test is considered the best overall measure of kidney function in primary care?

Estimated Glomerular Filtration Rate (eGFR).

What eGFR value defines CKD when present for 3 or more months?

eGFR <60 mL/min/1.73 m2 for 3 months or more (or evidence of kidney damage with eGFR ≥60).

What are the two main equations historically used to calculate eGFR and what change occurred in 2021?

MDRD and CKD-EPI equations; 2021 CKD-EPI creatinine equation removed race coefficient.

How does serum creatinine relate to GFR?

Creatinine increases as GFR decreases; they are inversely related.

What is creatinine clearance and why is it used?

A 24-hour urine test to estimate renal function over a day; more sensitive than single serum creatinine and doubles for every 50% reduction in GFR.

When can serum creatinine be falsely low?

In people with low muscle mass (e.g., older adults).

What is BUN and its limitation as a renal function marker?

Blood Urea Nitrogen; reflects kidney excretion of urea but is less sensitive than creatinine/eGFR and affected by diet and liver function.

What does an elevated BUN:creatinine ratio suggest?

Decreased kidney perfusion (prerenal state).

What are the three components of a complete urinalysis (UA)?

Gross evaluation, dipstick analysis, and microscopic examination of urine sediment.

What does a large number of squamous epithelial cells in urine indicate?

Contamination of the urine sample.

What constitutes normal white blood cells in urine and what does leukocyte esterase indicate?

Normal WBCs in urine: roughly ≤2–5 WBCs per high-power field; leukocyte esterase indicates presence of WBCs.

What does the presence of nitrites in urine indicate?

Bacteria that reduce nitrates; positive nitrites are highly indicative of a UTI (Enterobacteriaceae).

What do renal casts indicate and what are the main types?

Casts are tubular-shaped; hyaline casts are nonspecific; WBC casts (pyelonephritis/interstitial nephritis); RBC casts (glomerulonephritis).

What is the normal urine pH range and why is it tested?

Reference range 4.5 to 8.0; used in evaluating stones and infections; diet can affect pH.

What defines a positive urine culture for a UTI?

≥10°5 CFU/mL of one dominant organism; multiple organisms may indicate contamination; lower values may still indicate bacteriuria.

How are Chronic Kidney Disease (CKD) stages defined by GFR?

Stage I: ≥90; Stage II: 60–89; Stage IIIa: 45–59; Stage IIIb: 30–44; Stage IV: 15–29; Stage V: <15 mL/min/1.73 m2.

What is AKI and its typical duration based on KDIGO guidelines?

Acute kidney injury is an abrupt decline in kidney function; duration often 7–21 days, with some patients recovering sooner or needing dialysis.

What are the main diagnostic features of AKI?

Rapid changes in serum creatinine and/or reduced urine output as defined by KDIGO criteria.

What are the general components of AKI management?

Eliminate nephrotoxic insults, treat hypovolemia, correct electrolyte disturbances and acidosis, provide nutrition, and refer to ED/nephrology.

List common nephrotoxic drugs mentioned in the notes.

Acyclovir, Allopurinol, Aminoglycosides (vancomycin), Antiretrovirals, Beta-lactams, Chemotherapeutics, Contrast dyes, Diuretics, Drugs of abuse, Lithium, NSAIDs, Proton pump inhibitors, Quinolones, Sulfonamides.

What defines pre-renal AKI and its common etiologies?

Prerenal AKI due to hypoperfusion from causes like hypovolemia, decreased cardiac output, or drugs that reduce GFR (ACE inhibitors, NSAIDs).

What defines intrinsic (intra-renal) AKI and its common cause?

Damage to kidney tissues such as tubules or interstitium; ATN is a common intrinsic cause and is often reversible.

What defines post-renal AKI and its common etiologies?

Obstruction of urine flow in the renal tubules to the urethra; etiologies include bladder outlet obstruction, stones, strictures, and neurogenic bladder.

What is the classic presentation and management approach for acute pyelonephritis outpatient vs inpatient?

Outpatient: milder infection treated with oral antibiotics; inpatient for complicated cases or inability to tolerate oral meds; empiric therapy depends on severity and resistance risk.

What is the most common cause of acute pyelonephritis in adults?

Gram-negative Enterobacteriaceae, especially E. coli.

What is asymptomatic bacteriuria (ASB) and when is it treated?

Presence of bacteria in urine ≥10^5 CFU/mL without UTI symptoms; treated in pregnancy, prior to urologic intervention, or renal transplant recipients; not routinely treated in older adults, diabetes, catheterized patients, or non-urologic surgery.

What defines acute simple cystitis in adult females and first-line treatment options?

Dysuria, frequency, nocturia; UA may show leukocytes and nitrites; first-line treatments include nitrofurantoin, TMP-SMX, or fosfomycin depending on resistance risk.

What is postcoital UTI prophylaxis and the recommended agents?

Single-dose antibiotics after intercourse: nitrofurantoin, TMP-SMX, trimethoprim, or cephalexin.

What is a key consideration in acute simple cystitis in adult males?

Often involves underlying structural issues (urethral stricture, BPH, stones); evaluate for STIs if sexually active (NAAT for gonorrhea/chlamydia).

What is the most common stone type and its prevalence?

Calcium oxalate stones comprise about 70–80% of stones; calcium phosphate about 15%; other types include uric acid, struvite, and cystine.

List major modifiable risk factors for calcium stones.

Low urine volume, high calcium, high oxalate, low citrate, high sodium and protein intake, high sugar (sucrose/fructose), low fluid intake.

List major non-modifiable risk factors for calcium stones.

Family history/genetics and White race.

Describe the classic renal colic pain pattern.

Severe, colicky flank pain on one side that comes in waves; pain may cause patient to pace; often associated with nausea/vomiting and hematuria.

What imaging modality is preferred for suspected kidney stones and alternatives if not available or pregnancy?

Noncontrast CT is preferred; renal ultrasound is an alternative if CT is unavailable or in pregnancy.

How is stone size used to guide management and what therapies are used?

Stones ≤5 mm: likely pass spontaneously with hydration; 5–10 mm: consider tamsulosin for up to 4 weeks; >10 mm: urology consult; ESWL for larger stones.

What dietary advice helps prevent calcium oxalate stones?

Increase fluids to 2–3 L/day; avoid high-oxalate foods (rhubarb, spinach, okra, nuts, beets, chocolate, tea).

How is proteinuria defined and what is the gold-standard test to quantify it?

Defined as >150 mg/day of protein; 24-hour urine collection is the gold standard for quantifying protein excretion.

What are the four types of proteinuria?

Glomerular, tubular, overflow, and postrenal proteinuria.

What is the significance of urine albumin-to-creatinine ratio (ACR) and protein-to-creatinine ratio (PCR) in CKD?

Used to quantify albuminuria and proteinuria, important for CKD staging and prognosis.

When should nephrology consult be considered in CKD?

eGFR

What diet is commonly recommended for CKD patients?

Dietary Approaches to Stop Hypertension (DASH)-style diet; tailored nutrition with restrictions on potassium, phosphorus, and fluid as indicated.

What are common laboratory abnormalities seen with advanced CKD?

Anemia, hyperphosphatemia, hyperkalemia, metabolic acidosis, hypocalcemia, elevated parathyroid hormone.

What is contrast-associated AKI and when does it typically occur after contrast exposure?

Rise in serum creatinine occurring after iodinated contrast, typically within 24–48 hours.

What is the imaging modality with the highest sensitivity/specificity for kidney stones?

Noncontrast CT is the most sensitive/specific imaging test for stones; renal ultrasonography can be used initially or in pregnancy.

What precaution should be taken when starting ACE inhibitors or ARBs in patients with CKD?

Monitor serum potassium after initiation, as potassium can rise especially with existing kidney disease.

How is CKD risk assessed in relation to urinary findings and imaging?

Assess proteinuria/albuminuria, eGFR trajectory, anemia, bone-mineral metabolism; ultrasound or vascular duplex may be used to evaluate structural or vascular causes.

What are signs that may indicate glomerular bleeding in hematuria?

Gross hematuria with absence of blood clots may suggest glomerular origin; RBC casts on urine sediment support glomerulonephritis.

What constitutes poststreptococcal glomerulonephritis in the clinical context?

New dark reddish-brown urine with edema after a recent streptococcal infection, usually within 10 days to 3 weeks; more common in children.

What is the role of urine cytology in evaluating hematuria?

Used when malignancy is suspected (urothelial/renal cancer) and may guide nephrology referral.

What are common risk factors for urothelial or renal malignancy?

Age >50, male sex, smoking, and gross hematuria.

When should urine C&S be performed in UTIs?

For persistent symptoms, atypical presentations, recurrence, or when initial therapy fails; in uncomplicated acute cystitis in healthy women, C&S is often unnecessary.

What are common risk factors for UTIs in females?

Female sex, pregnancy, history of UTI, diabetes/immunocompromise, incomplete voiding after sex, spermicide use, poor hygiene, catheterization.

What is the typical initial management for uncomplicated UTIs in healthy women without resistance risk?

UA-guided assessment; first-line antibiotics include nitrofurantoin, TMP-SMX, or fosfomycin for specified durations.

What is a key consideration in the management of recurrent UTIs in women?

Avoid unnecessary antibiotic prophylaxis as first-line therapy; evaluate for underlying abnormalities, and emphasize hydration and postcoital strategies.

Why is nitrofurantoin sometimes contraindicated or used with caution?

Not recommended in patients with renal insufficiency; potential for lung, liver, or neuropathic toxicity with long-term use.

What is the typical approach to postmenopausal women with recurrent UTIs?

Topical vaginal estrogen, increased fluids, postcoital antibiotic prophylaxis as described; lifestyle measures and hydration are emphasized.

What factors define asymptomatic bacteriuria management in pregnancy?

ASB should be screened and treated in pregnancy due to risk to mother and fetus; not routinely treated in certain other populations.

What is the relationship between eGFR and age, sex, and body size?

eGFR decreases with age; sex differences exist (males often have higher muscle mass); body size affects GFR estimates.

What are typical clinical signs of CKD progression on physical exam?

Volume overload signs (edema, weight gain, dyspnea) or volume depletion signs (dry skin, tachycardia); abdominal bruit may suggest renal artery stenosis.

What is the DASH diet in CKD care?

A diet pattern similar to DASH, often recommended for blood pressure control and renal health, with individual nutrient restrictions as needed.

Which symptoms and tests support a diagnosis of nephrolithiasis (kidney stones) in the classic case?

Severe colicky flank pain with nausea/vomiting, hematuria; UA may show blood; CT without contrast confirms stone presence and size.

What is the typical treatment course for a small kidney stone (≤5 mm)?

Conservative management with hydration and analgesia; most pass spontaneously.

What pharmacologic option facilitates passage of 5–10 mm stones?

Tamsulosin (an alpha-blocker) for up to 4 weeks (or other alpha-blockers/calcium channel blockers as alternatives).

What imaging finding supports acute kidney stone management decisions besides CT?

Ultrasound can detect hydronephrosis and stones when CT is not available or contraindicated (e.g., pregnancy).

What are common dietary blockers for calcium stone recurrence?

Increasing fluids; limiting foods high in oxalate (e.g., rhubarb, spinach, beets, nuts, chocolate, tea); balanced calcium intake as advised.

What is the role of urine culture in suspected UTI?

Confirms bacteriuria and identifies antibiotic susceptibility; a clean-catch specimen is used; threshold CFU/mL defines positivity.

What is the importance of leukocyte casts in UA?

WBC casts are associated with pyelonephritis or interstitial nephritis and indicate renal involvement by infection or inflammation.

What is the importance of proteinuria in CKD evaluation?

Proteinuria indicates kidney damage; quantifying proteinuria helps stage CKD and assess progression and risk.

What is the relevance of renal ultrasound and vascular duplex in CKD evaluation?

Ultrasound detects structural abnormalities; vascular duplex evaluates for renal artery stenosis.

What are warning signs that would prompt ED referral in AKI or CKD patients?

Hypervolemia with pulmonary edema, severe hyperkalemia, life-threatening uremic symptoms, suspected toxin exposure, rapid GFR decline.