Nephrology Flashcards
What is defined as microscopic hematuria?
Microscopic hematuria is >3RBC/rpf
Gross, painless hematuria is ____ until r/o
Bladder cancer
A urine that is +ve by dipstick but neg on microscopy should be suspicious for?
Free Hb or myoglobin
What is a very common cause of transient hematuria in <35yo?
Vigorous exercise
The most common causes of hematuria?
- Urinary tract infections (UTIs)
- Prostatitis
- Urinary calculi (in adults)
- Congenital or acquired anatomic abnormalities
- Cancers
Etiology of hematuria?
- Glomerular: glomeruloneophritis, IgA nephropathy, HUS, lupus
- Infectious/Inflammatory: Pyelonephritis, Cystitis, Urethritis, Glomerulonephritis Interstitial nephritis, Tuberculosis
- Malignancy: RCC (mainly adults), Urothelial cancer, Wilms’ tumour (mainly pediatric) Prostate cancer
- Benign: BPH, Polyps, Exercise- induced
- Structural: Stones, Trauma, Foreign body, Urethral stricture, Polycystic kidneys, Arteriovenous malformation, Infarct, Hydronephrosis, Fistula
- Hematologic: Anticoagulants, Coagulation defects, Sickle cell disease, Thromboembolism
What are some causes of pseudohematuria?
- Vaginal bleeding
- Dyes (beets, rhodamine B in candy and juices)
- Hemoglobin (hemolytic anemia)
- Myoglobin (rhabdomyolysis)
- Drugs (rifampin, phenazopyridine, phenytoin)
- Porphyria
- Laxatives (phenolphthalein)
Important aspects to gather on history for hematuria?
- Timing of hematuria in urinary stream
- Urinary obstructive symptoms and irritative symptoms
- Last menstrual period, history of kidney stones, UTI, or previous urologic surgery
- Hearing loss (Alport syndrome), rashes (connective tissue disorder)
- Recent URTI, post-infectious glomerulonephritis, IgA nephropathy
- Medications (anticoagulants, rifampin, phenazopyridine, phenytoin)
- Risk factors for malignancy (smoking, chemical exposures, Hx of cyclophosphamide therapy, pelvic radiation)
- FHx: Stone disease
Physical exam for hematuria?
- Vitals (fever + HTN)
- Abdomen (masses; flanks should be percussed for tenderness over the kidneys)
- DRE
- Face and extremities should be inspected for edema (suggesting a glomerular disorder)
- Skin should be inspected for rashes (suggesting vasculitis , SLE , or immunoglobulin A–associated vasculitis).
Cystitis predominantly shows what on UA?
RBCs
What are the 4 Cs you test for with microscopic hematuria
- 4 Cs after microscopic hematuria: culture (UTI), cytology (malignancy), CT urogram (nephrolithiasis, renal massues, filling defects), cystoscopy
Besides the 4Cs and microscopic UA what else should be ordered?
- CBC (rule out anemia, leukocytosis), electrolytes, Cr, BUN, INR, PTT, PSA (in men >50)
Patients < 50 with gross hematuria or unexplained systemic symptoms require?
Cystoscopy +/- CT of the abdomen and pelvis.
If microscopic UA shows: proteinuria, dysmorphic RBC, tea/coke colour, RBC casts
Send to nephrology
If microscopic UA shows: red urine, monomorphic RBCs, no proteinuria + lower urinary tract Sx
Send to urology
Hematuria: Glomerular disorders are often accompanied by?
Edema, hypertension, or both; symptoms may be preceded by an infection (particularly a group A beta-hemolytic streptococcal infection in children).
Hematuria: Calculi usually manifest with
Excruciating, colicky pain
Hematuria: Urinary obstructive symptoms in man usually suggest
Prostate disease.
Hematuria: Urinary irritative symptoms suggest
Bladder or prostate infection
Hematuria: An abdominal mass suggests
Polycystic kidney disease or renal cell carcinoma .
Acute management of severe bladder hemorrhage
- Manual irrigation via catheter with normal saline to remove clots
- Continuous Bladder Irrigation (CBI) using large (22-26Fr) 3-way Foley to help prevent clot formation (after manual irrigation of clots)
- Cystoscopy
- Identify tumours or other source(s)
- Coagulate obvious sites of bleeding or transurethral resection of tumours (under general or regional anesthesia)
Patients with unexplained microscopic hematuria require?
US
Definition of hyperkalemia?
Definition: K+ >5mmol/L
How to potassium excreted?
Urine excretion of K+ is regulated (in the CCD) and does 90% of the work, 10% is lost in poop/gut (but this can increase in CKD/diarrhea).
What are the symptoms + cardiac features of hyperkalemia?
MURDER With Tall Peak T wave
- Muscle weakness
- Urine, oliguria, anuria
- Respiratory distress (hypoventilation)
- Decreased cardiac contractility
- EKG changes
- Reflex (hyperreflexia)
- Cardiac/ECG: narrow, peaked T wave (especially precordial leads) + widened QRS + wide/flat P wave + V-fib
Ddx of hyperkalemia?
- Increased intake: Diet, KCl tabs, IV KCl, Salt substitute
- Shift out of the cell (metabolic acidosis + diabetes/insulin deficient + beta-blockade + cellular necrosis)
- ^release (rhabdomyolysis (breakdown of damaged skeletal muscle) + burns + tumor lysis + strenuous exercise + intravascular hemolysis)
- Decreased output (decreased tubular flow due to renal failure or effective circulating fluid volume, OR hypoaldosteronism due to decreased renin, adrenal insufficiency, type IV RTA, ACE inhibitors, ARBs, spironolactone, NSAIDs).
Most common causes of high [K+] are
- Reduced GFR (low flow or renal failure)
- Medications that interfere with aldosterone
- Hyporenin-hypoaldosteronism due to DM or CKD
2 major pathways leading to aldosterone secretion
- Renin-angiotensin pathway arising from volume signals
- Direct stimulation via sensing of plasma potassium concentration
Investigations for hyperkalemia?
- Basic Labs: CBCd (K and CO2) + lytes + Urea/Cr + urinalysis + urine lytes + urine osmolarity + serum osmolarity + CK
- Special Investigations: ECG (consider if K > 6.0) + ABG/VBG (quick way to get K level)
Hypoaldosteronism Workup: serum aldosterone + plasma renin activity
How to stabilize the myocardium for hyperkalemia?
Calcium chloride 10% 10ml IV push OR calcium gluconate 10% 10ml IV push; use CaCl if hemodynamically unstable, given that gluconate must be hepatically metabolized before calcium becomes bioavailable – don’t give if K>6 due to digoxin (causes V-fib!)
Treatment of hyperkalemia if [K+] <6.5 and normal ECG?
Treat underlying cause, stop K+ intake, increase the loss of K+ via urine and/or GI tract
Treatment of hyperkalemia if [K+] between 6.5 and 7.0, no ECG changes?
Treat underlying cause, stop K+ intake, increase the loss of K+ via urine and/or GI tract + insulin
Treatment of hyperkalemia if [K+] >7.0 and/or ECG changes?
Treat underlying cause, stop K+ intake, increase the loss of K+ via urine and/or GI tract + insulin + calcium gluconate
Besides D50W (dextrose) 50ml IV push followed by Humulin R (insulin) what else could you do to shift K into the cells for hyperkalemia?
- Consider high dose beta agonist (Ventolin) - onset of action 30-90 min, stimulates Na+/K+ ATPase
- Consider bicarbonate if severe metabolic acidosis, drives K+ into cells in exchange for H+
How to shift K into the cells for hyperkalemia?
D50W (dextrose) 50ml IV push followed by Humulin R (insulin) 10U in 50ml of D50% IV bolus; consider dextrose drip or second amp of D50W as hypoglycemia occurs in up to 70% of cases w/ 1 amp
How to enhance K+ removal for hyperkalemia?
- Via urine (preferred) - furosemide diuretic 40mg IV, doses up to 200mg may be needed in acute renal failure
- Via GI (if renal function is severely impaired): Cation-exchange resins: calcium resonium or sodium polystyrene sulfonate (Kayexalate®) (which is prescribed in conjunction with sorbitol)
- Lactulose or sorbitol PO to avoid constipation (must ensure that patient has a bowel movemen tafter resin is administered - main benefit may be the diarrhea caused by lactulose)
- Dialysis (renal failure, life threatening hyperkalemia unresponsive to therapy)
Which medications/drugs should be stopped with hyperkalemia?
Discontinue drugs like K supplements + ACEi + ARBs + spironolactone + NSAIDs + trimethoprim
What is the definition of hypokalemia?
K+ <3.5mmol/L
Symptoms and signs of hypokalemia?
- Muscular: weakness/paralysis (periodic); may include extremities, resp/GI muscles = cramps, paresthesia, tetany, muscle tenderness, atrophy, and rhabdomyolysis may develop
- Cardiac arrythmias
- GI: N/V, constipation or ileus, fatigue
- Hyperglycemia (decreased peripheral glucose uptake and impaired insulin release) + polyuria (impaired ADH)
Most common causes of low [K+] are
- Loop or Thiazide Diuretics (increase Na+ delivery distally and induce low ECFV → high aldosterone)
- GI fluid losses (lose K+ from the gut and induce low ECFV → high aldosterone)
Ddx of hypokalemia?
- Decreased intake
- Shift into the cell (metabolic alkalosis (Response: exchange of hydrogen ions for potassium from cells) + hyperinsulin states (shifts potassium into cells by stimulating the activity of Na+-H+ antiporter on cell membrane) + increased beta-adrenergic states + hypothermia)
- Increased output
- GI loss due to diarrhea/vomiting/tube draining/laxatives
- Renal loss – hyperaldosteronism (Conn’s/renal artery stenosis), Non-aldosterone mineralocorticoid (Cushing’s, exogenous), Diuretics (furosemide, HCTZ) manifest as renal losses due to hyperaldosteronism, metabolic alkalosis, and increased flow to collecting duct
- Can be drug induced (K+ supplements, ACE-i, ARB, NSAIDs) esp. with renal impairment
Investigations for hypokalemia?
- Lytes + extended lytes (Ca/Mg/Phosphate) + Urea/Cr + urinalysis + urine lytes + urine osmolality + serum osmolarity + glucose + troponin/CK,
- Check BP
- Spot urine K:Cr
- Special Investigations: ECG
- Hyperaldosteronism Workup: serum aldosterone + plasma renin activity)
If spot urine K:Cr <1.5 mEq/mmol consider
GI loss
If spot urine K:Cr >1.5 mEq/mmol consider
Renal loss
Treatment for hypokalemia?
- Treat underlying cause
- If true K+ deficit, potassium repletion
- Oral sources - food, tablets (K-DurTM), KCl liquid solutions (preferable route if the patient tolerates PO medications)
- IV - usually KCl in saline solutions, avoid dextrose solutions (may exacerbate hypokalemia via insulin release)
- Max 40 mmol/L via peripheral vein,60 mmol/L via central vein, max infusion 20 mmol/h
- K+-sparing diuretics (triamterene, amiloride, spironolactone) can prevent renal K+ loss
- Restore Mg2+ before correcting K+ - MgSO4 5g IV over 4 hours
- Use ACE inhibitor or ARB for CHF (reduces angiotensin II action and therefore reduces aldosterone production)
What is the definition of proteinuria?
> 150mg/d of protein (usually <30mg of albumin per day, primarily Tamm Horsfall mucoprotein)
What is the gold standard to quantify proteinuria?
24 Hour Urinary Protein
In general, greater than 2.0g/24hr is diagnostic of ____ on dipstick (+) urine. Less than 1.0g however is unhelpful as it could be tubular or glomerular in origin.
Glomerular disease
What is commonly used to calculate how much proteinuria is present?
Spot Protein:Creatinine Ratio (PCR or ACR): to estimate daily protein excretion in mg
Normal PCR and ACR amounts?
- PCR: normal is <13mg/mmol
- ACR: normal is <2mg/mmol for men but <2.8mg/mmol for women
- To get that 24hr amount, simply multiply the ratio by the mmols of creatinine excreted per day in the urine: for men it is 15-20, for women it is 10-15 (e.g. ACR 24 hr is 2 x 15 for man = 30). Should always be measured at the SAME TIME OF DAY (first morning void).
What test can you do to determine the type of proteinuria present?
- UPEP (Urine protein electrophoresis helps you determine the type of protein (albumin, IgG, Tamm-Horsfaall).
- Protein gap. If you do not have UPEP, you can compare PCR to ACR (i.e. the protein gap). E.g. if ACR low, then think about non-albumin proteinuria. If ACR is <40% of PCR – may indicate unmeasured proteins
Pathophysiology of proteinuria?
- Glomerular Proteinuria
- Functional proteinuria
- Orthostatic/Postural
- Tubular Proteinuria
- Overflow Proteinuria
Causes of glomerular proteinuria?
- Primary glomerular disorders (membranous nephropathy, minimal change disease, focal segmental glomerulosclerosis)
- Secondary glomerular disorders (diabetic nephropathy, preeclampsia, postinfectious glomerulonephritis, lupus nephritis, amyloidosis)
The most common causes of proteinuria (and nephrotic syndrome) in adults are
Focal segmental glomerulosclerosis, Membranous nephropathy, Diabetic nephropathy
What should be asked on history for proteinuria?
- Ankle swelling + fever + strenuous exercise + UTIs (FUND – frequency, urgency, nocturia, dysuria)
- Vasculitis (rash, joint pain)
- New diagnosis of DM
- Connective tissue disease (Raynaud’s, photosensitivity, oral ulcers)
- PMHx - myeloma, DM, glomerulonephropathies, SLE
- Meds - NSAIDs/Antibiotics