What are the next steps for a patient with impaired renal function, elevated BUN, and abnormal electrolyte levels?

Immediate Management of Advanced Kidney Failure with Electrolyte Abnormalities

This patient requires urgent nephrology referral and consideration for renal replacement therapy (RRT) given GFR 18 mL/min/1.73 m² with uremic complications (BUN 63, metabolic acidosis). 1

Urgent Nephrology Referral

• Immediate nephrology consultation is indicated for GFR <30 mL/min/1.73 m² with progressive decline, severe electrolyte abnormalities, and metabolic acidosis 1
• The Canadian Society of Nephrology recommends referral at GFR <30 mL/min/1.73 m² for planning RRT, particularly when risk of kidney failure within 1 year is 10-20% or higher 1
• This patient's GFR of 18 mL/min/1.73 m² represents Stage 5 CKD (kidney failure), requiring urgent specialist evaluation 2

Critical Laboratory Monitoring

Electrolytes must be monitored every 6-12 hours initially given the severity of kidney dysfunction and risk of life-threatening complications 3:

• Potassium monitoring is essential - while currently 4.3 mEq/L (acceptable), hyperkalemia >6 mmol/L requires continuous cardiac monitoring and urgent treatment with insulin/glucose, calcium, and potentially dialysis 4
• Sodium (133 mEq/L) - mild hyponatremia is common in kidney failure due to impaired water excretion and requires fluid management adjustment 3
• Bicarbonate (20 mEq/L) - metabolic acidosis is present and associated with cardiovascular morbidity; regular monitoring is recommended 1
• Calcium (8.1 mg/dL) - hypocalcemia is expected in advanced CKD due to impaired vitamin D metabolism and should be monitored with phosphorus levels 3

Medication Review and Optimization

Immediately review and adjust all medications for kidney function 1:

• Stop or dose-adjust nephrotoxic medications (NSAIDs, aminoglycosides, ACE inhibitors/ARBs if causing acute deterioration) 1
• Avoid potassium-sparing diuretics (spironolactone) given risk of hyperkalemia with GFR <30 5
• Consult pharmacy for dose adjustments of all renally-cleared medications 1
• Discontinue calcium supplements and calcium-based antacids to avoid hypercalcemia risk 6

Assess Volume Status and Fluid Management

Clinical examination for volume status is critical to guide fluid management 1:

• Evaluate for dehydration (BUN 63 suggests possible prerenal component): check peripheral perfusion, capillary refill, pulse, mucous membranes 1, 7
• Assess for fluid overload: examine for peripheral edema, pulmonary congestion, jugular venous distension 1
• Monitor 24-hour urine output - should be at least 0.8-1 L/day if not oliguric 1
• If dehydrated, cautious intravenous fluid administration may improve prerenal component 7

Address Uremic Complications

BUN 63 mg/dL indicates significant uremic toxin accumulation requiring intervention 8:

• High BUN independent of GFR is associated with anemia development and increased morbidity 8
• Assess for uremic symptoms: altered mental status, pericarditis, bleeding diathesis, nausea/vomiting 1
• Consider dietary protein restriction (0.6-0.8 g/kg/day) to reduce nitrogenous waste if not yet on dialysis 8
• Evaluate for uremic indications for urgent dialysis: refractory acidosis, hyperkalemia, volume overload, uremic symptoms 1

Metabolic Acidosis Management

Bicarbonate 20 mEq/L represents metabolic acidosis requiring monitoring and potential treatment 1:

• Regular monitoring of acid-base status (chloride and bicarbonate) is recommended in advanced CKD 1
• Metabolic acidosis contributes to cardiovascular morbidity and reduced quality of life 2
• Consider sodium bicarbonate supplementation if bicarbonate persistently <22 mEq/L 2

Prepare for Renal Replacement Therapy

Multidisciplinary RRT planning should begin immediately at this GFR level 1:

• Discuss RRT options: hemodialysis, peritoneal dialysis, kidney transplantation, and conservative management 1
• Arrange vascular access evaluation for hemodialysis (arteriovenous fistula preferred, requires 3-6 months maturation) 1
• Provide patient education about dialysis modalities and transplant options 1
• Establish advance care planning and treatment goals 1

Common Pitfalls to Avoid

• Do not delay nephrology referral - late referral (<1 year before dialysis) is associated with increased initial morbidity and mortality 1, 9
• Avoid aggressive potassium supplementation despite normal current level, as hyperkalemia can develop rapidly with declining kidney function 3
• Do not overlook calcium-phosphorus product - maintain Ca x P <55 mg²/dL² to prevent vascular calcification 6
• Avoid volume depletion from excessive diuresis which can worsen kidney function 5
• Monitor for hypoglycemia if diabetic, as insulin is partially metabolized by kidneys 3