Penn Pearls

Renal

Disclaimer: the clinical information on this site is only meant to serve as a reference. Please consult with your team for individual diagnostic and treatment decisions.

Acute Kidney Injury (AKI)

• Differential: prerenal (volume depletion from dehydration or overdiuresis or bleeding, cardiorenal from CHF leading to poor arterial forward flow to kidneys, renal artery stenosis), intrinsic renal (ischemic event such as septic shock, contrast, tumor lysis syndrome, acute interstitial nephritis from pain medications or certain antibiotics, glomerulonephritis/nephrotic syndrome, transplant rejection, fat embolism, rhabdomyolysis), or postrenal (urinary retention with hydronephrosis, BPH, kidney stones)
• Diagnostic workup: UA/urine culture, urine FeNa or FeUrea (urine sodium and creatinine if did not receive recent diuretics, urine urea and creatinine if did get recent diuretics, to look for prerenal state), urine protein/creatinine (random spot sample first, then if abnormal consider 24hr collection), bladder scans with possible Foley placement, empiric fluid trial, empiric diuretic trial (if felt to be from nephrotic syndrome or cardiorenal CHF syndrome), tumor lysis syndrome or rhabdomyolysis or transplant rejection labs (if applicable), consider saving a urine sample for renal to centrifuge and look at under microscope
• If requires central line to leave the hospital (ex: PICC line) and renal function still very compromised, consider IR small bore central catheter (placed very proximally to preserve veins needed for future HD access)

Chronic Kidney Disease (CKD) Classifications

• Can access GFR and estimated creatinine clearance in EPIC in the top right corner or in each individual BMP lab result, normal ranges differ between African Americans and non-African Americans
• Grade and stage have the same GFR (glomerular filtrate rate) criteria but grade criteria adds an A1, A2, or A3 designation based on level of proteinuria
• Grade or stage (by GFR): Grade/Stage 1 (>=90), Grade/Stage 2 (60-89), Grade/Stage 3a (45-59), Grade/Stage 3b (30-44), Grade/Stage 4 (15-29), Grade/Stage 5 (<15 or on dialysis)
• Generally only replete potassium and magnesium halfway to goal (ex: K 3.2 would be repleted to 3.6 rather than 4.0)
• If requires central line to leave the hospital (ex: PICC line), strongly consider IR small bore central catheter (placed very proximally to preserve veins needed for future HD access)

Dialysis (ESRD, Acute Renal Failure, New Start HD, Peritoneal)

• If chronic dialysis, contact renal dialysis team to get onto schedule and discuss if volume overload is also an issue (requires extra ultrafiltration or nearly daily dialysis)
• Clarify if the patient receives dialysis through a tunneled HD catheter, AV graft/fistula, or peritoneal dialysis catheter
• Vascular hemodialysis (HD) has the capability to remove fluid via ultrafiltration
• Peritoneal dialysis (PD) usually removes much less fluid (these patients often still produce reasonable amounts of urine)
• If a dialysis patient requires emergent diuresis, first clarify if they are anuric (<100cc/day) or oliguric (<400cc/day) and consider using a high dose from the start (ex: Lasix 80-120mg IV)
• Unless moderate to severe hypokalemia or hypomagnesemia, usually we do not replete K/Mg and allow the dialysate solution to be adjusted or if repletion is needed we will usually replete halfway to goal
• For new dialysis starts due to symptomatic uremia or oliguric/anuric renal failure, ICU patients on pressors will start on CRRT (continuous renal replacement therapy) aka CVVHD (continuous veno-venous hemodialysis) while floor patients without hypotension will start hemodialysis via vascular access. If any possibility of systemic infection or bacteremia place non-tunneled HD line by primary team or procedure team first and when no longer concerned (last blood cultures must be >48-72hrs ago even if done for surveillance) can switch to tunneled HD line by IR (can go straight to tunneled HD line if no concern for infection and felt to have slowly progressive CKD as outpatient unlikely to recover). Must stay in hospital for 3 HD sessions to prove hemodynamic stability, determine dialysate electrolyte levels, and monitor for dialysis disequilibrium syndrome. Contact the dialysis social worker to begin sending referrals to dialysis facilities and insurance authorization. As an outpatient may get vascular mapping (for graft/fistula sites) and vascular surgery for placement of graft/fistula.
• If requires central line to leave the hospital (ex: PICC line), strongly consider IR small bore central catheter (placed very proximally to preserve veins needed for future HD access)

Hematuria

• Differential: extrarenal (Foley trauma, infection like UTI/cystitis/urethritis/prostatitis, bladder or prostate cancer) or intrarenal (nephrolithiasis, crystalluria, renal cell carcinoma, trauma, glomerulonephritis, renal infarct)
• Consider CBI (continuous bladder irrigation) with urology guidance if severe, may need to flush Foley intermittently to prevent clots in Foley leading to obstruction and bladder spasms

Hyponatremia

• Diagnosis via clinical history: could be low PO intake, diuretics, third-spacing from hypoalbuminemia/CHF/cirrhosis/nephrotic syndrome, from dialysate solution, SIADH if recent brain manipulation, severe hyperglycemia, adrenal insufficiency, primary polydipsia (water intoxication)
• Diagnosis via labs: if serum osmolality is normal consider pseudohyponatremia, hyperlipidemia, hyperproteinemia, or renal failure. If serum osmolality is elevated consider hyperglycemia or mannitol. If serum osmolality low (most of the time) then check urine osmolality. If urine osmolality < 100mOsm/kg consider primary polydipsia, malnutrition, or reset osmostat. If urine osmolality > 100mOsm/kg then there is impaired free water excretion and need to send urine sodium. If urine sodium > 40 mEq/L (assuming no recent confounding by diuretics) then consider SIADH, thiazide use, renal failure, or adrenal insufficiency. If urine sodium <25 mEq/L consider hypovolemia, CHF, or cirrhosis.
• Treatment: fluids if felt to be from hypovolemia, salt tabs +/- Lasix and with fluid restriction for SIADH, stopping offending drugs, treating hyperglycemia, or diuresis (if hypervolemic from CHF/nephrotic/cirrhosis)

Hypernatremia

• Differential: usually from hypovolemia (poor free water intake, insensible losses from respiratory distress or fevers, or overdiuresis) and sometimes from diabetes insipidus (especially if brain manipulation)
• Can calculate free water deficit and correct over about 48 hrs using age, gender, weight, and serum sodium level (https://www.mdcalc.com/sodium-correction-rate-hyponatremia-hypernatremia)

Hypokalemia

• Differential: GI losses (vomiting/diarrhea), diuretic-induced, poor PO intake and refeeding syndrome, intracellular shifts from DKA, less commonly hyperaldosteronism or renal tubular acidosis
• Goal is around 4.0 mEq/L but if no drop expected (ex: no diuresis) then above 3.5 mEq/L usually doesn’t need repletion
• For dialysis/severe CKD: consider repleting only halfway (if 3.2 then replete up to 3.6 instead of 4.0)
• Potassium chloride PO: 10mEq raises K by 0.1 mEq/L (max 60mEq at once)
• Potassium chloride IV: 10mEq raises K by 0.1 mEq/L (max 60mEq at once, central line formulation comes with less fluid than peripheral line formulation, every 10mEq IV takes 1 hour to infuse)

Hyperkalemia

• Differential: pseudohyperkalemia (tapping phleobotomy site or hemolysis within blood sample vial), dietary indiscretion, AKI/CKD/ESRD, medication induced (ACEI, ARB, spironolactone), rhabdomyolysis, tumor lysis syndrome
• EKG: obtain EKG if potassium >=5.5 mEq/L
• Mneumonic for treating hyperkalemia: “C BIG K and DD”
• C=calcium gluconate (give if K>=6.0) or if any EKG changes of hyperkalemia to stabilize the cardiac membrane potentials (temporary treatment)
• B=beta-agonist (10-15 puffs of albuterol inhaler) or =bicarbonate (sodium bicarbonate IV bolus or drip) both of which causes only a temporary intracellular potassium shift (through K+ movement or H+/K+ movement) (temporary treatment)
• IG=insulin/glucose or dextrose so give 10 units REGULAR IV insulin (not subcutaneous aspart) with an amp of D50 which only causes a temporary intracellular potassium shift since insulin and potassium move together (temporary treatment)
• K=Kayexalate (polystyrene sulfonate) 30 grams via oral liquid, causes diarrhea to excrete potassium, careful in anyone with short gut syndrome or prone to severe constipation or bowel obstruction (can cause bowel ischemia if stays in one place too long) (permanent treatment)
• D=diuretics (Lasix, Bumex, torsemide) and if needed can be given with fluids to prevent dehydration (permanent treatment)
• D=dialysis (permanent treatment)

Hypomagnesemia

• Differential: diarrhea, poor PO intake, tacrolimus magnesium wasting
• Goal is around 2.0 mg/dL but if no drop expected (ex: no diuresis) then 1.8 mg/dL usually doesn’t need repletion
• For dialysis/severe CKD: consider repleting only halfway (if 1.2 then replete up to 1.6 instead of 2.0)
• Magnesium oxide PO: 400mg raises Mg by about 2.0-2.5 mg/dL (max 800mg at a time, causes diarrhea)
• Magnesium sulfate IV: 1gm raises Mg by 0.1 mg/dL (max 4mg at a time, every 1gm IV takes 1 hour to infuse)

Renal Transplant Primer

• For transplant pyelonephritis, reminder that the transplanted kidney is placed in the lower anterior abdomen so the patient may not have CVA tenderness with pyelonephritis and may have lower abdominal pain and may not have dysuria if bladder sensation is affected by the surgery
• For fevers consider CMV viremia and BK virus
• For diarrhea consider CMV colitis (serum level and possibly colonoscopic biopsy)
• For AKI consider transplant rejection or BK virus
• Common transplant medications: tacrolimus aka Prograf (can be replaced by sirolimus aka Rapamycin or cyclosporine aka Gengraf), prednisone, and mycophenolate mofetil aka Cellcept
• Tacrolimus aka Prograf: calcineurin inhibitor, make sure blood level is drawn first and then dose is given, timed to 6am/6pm in EPIC to coincide with blood draws, goal level 4-8 depending on organ transplanted and time since transplant, often still needs immunosuppression if transplant has failed but organ remains within the body, can cause magnesium wasting, squamous cell carcinoma of the skin, AKI, hyperkalemia, posterior reversible encephalopathy syndrome (PRES) presenting as headache and hypertension, and post-transplant lymphoproliferative disorder (type of B-cell lymphoma)
• Prednisone: carries risk of hyperglycemia, osteoporosis, fungal infections including PCP and Aspergillus, adrenal insufficiency
• Mycophenolate mofetil aka Cellcept: side effects (nausea, diarrhea, leukopenia), often the first transplant drug to be held while actively infected or having GI symptoms

Urinary Tract Infection (UTI)/Pyelonephritis

• UA usually with 20-50 WBC and minimal squamous epithelial cells, leukocyte esterase/nitrites may be possible. 10-20 WBC is a gray area. Neutropenic patients may not mount WBC in the urine. Ensure it’s a clean collection and if the patient has a Foley that the Foley is changed before drawing a UA/urine culture. Ideally cultures are collected pre-antibiotics.
• Uncomplicated UTI: no recent antibiotic use or healthcare exposure and not a male.
• Complicated UTI: recent healthcare exposure, catheter-associated, immunosuppressed, recent antibiotic use, urologic anatomic issue, pregnant, or male.
• Pyelonephritis: may have CVA (costovertebral tenderness), may have perinephric stranding on ultrasound/CT, remember kidney transplant patients have their transplanted kidney graft in the lower anterior abdomen so they will have anterior abdominal pain and may have no dysuria due to nerves being cut during the transplant surgery, treatment is based on culture data.
• UPHS Antibiotic Stewardship Guidelines for Empiric Treatment/Sensitivities