What are the next steps for an elderly patient with a history of COVID-19, prolonged ICU (Intensive Care Unit) stay, and renal failure, who has impaired renal function (GFR 42), elevated creatinine (1.3), and normal blood sugar control (HGA1C 5.5), and is scheduled for follow-up with the nephrology group?

Management of Post-COVID Renal Impairment in an Elderly Patient

Your plan to send a nephrology referral with labs is appropriate, and you should also ensure nephrotoxin review, monitor electrolytes closely, and optimize blood pressure control while this patient awaits specialist evaluation.

Immediate Actions Beyond Nephrology Referral

Medication Review and Nephrotoxin Management

• Stop all NSAIDs immediately if the patient is taking any 1, 2
• Review and hold ACE inhibitors or ARBs during this period of renal impairment, as these medications can worsen kidney function when GFR is reduced 2, 3
• Discontinue metformin if the patient is taking it, given the GFR of 42 ml/min/1.73m² (threshold is <30, but caution is warranted at this level) 2
• Adjust doses of all medications based on current GFR of 42, particularly antibiotics, antivirals, or any other renally-cleared drugs 2

Laboratory Monitoring

• Measure serum creatinine, BUN, and electrolytes every 48 hours until stable or nephrology assumes care 4, 2
• Monitor potassium levels at least daily, as hyperkalemia is a significant risk with this level of renal impairment 1, 2
• Obtain urinalysis to check for hematuria, proteinuria, and casts to help differentiate the type of kidney injury 2

Volume Status Assessment

• Assess the patient's fluid status clinically to ensure euvolemia 4, 2
• Avoid both volume depletion and fluid overload, as COVID-19 patients with renal impairment have complex fluid management needs 1

Clinical Context and Prognosis

COVID-19 Related Renal Impairment

This patient's presentation is consistent with post-COVID renal impairment, which is common and carries significant prognostic implications:

• Renal impairment on admission and persistent kidney dysfunction are independent predictors of poor outcomes in COVID-19 patients 5
• Among critically ill COVID-19 patients, 44-58% develop acute kidney injury, with mortality rates of 25-50% in those with AKI compared to 6.7-21% in those without 6, 7
• The good news is that among survivors who had renal impairment, complete recovery of renal function occurs in the majority of cases 7

Stage 3a Chronic Kidney Disease

With a GFR of 42, this patient now has Stage 3a CKD (GFR 30-44 ml/min/1.73m²):

• This level of renal function requires careful medication dosing and monitoring 3
• The low calcium (9 mg/dL) may reflect early mineral bone disease and warrants monitoring 2

Indications for Urgent vs. Routine Referral

Your scheduled nephrology follow-up is appropriate given that:

• The creatinine is stable at 1.3 (not rapidly rising) 1
• The patient does not require dialysis 1
• There is no oliguria or anuria 1, 2

However, expedite the referral if any of the following develop:

• Worsening renal function despite conservative management 1, 2
• Persistent oliguria despite adequate fluid status 2
• Severe hyperkalemia or other electrolyte abnormalities 1
• Diagnostic uncertainty about whether this represents acute-on-chronic kidney disease 1

Common Pitfalls to Avoid

• Do not restart ACE inhibitors/ARBs without nephrology input in the setting of reduced GFR post-COVID 3
• Avoid assuming stable kidney function—COVID-19 related kidney injury can have delayed presentations and the long-term effects remain an area of uncertainty 1
• The BUN/Creatinine ratio of 14 suggests intrinsic renal disease rather than prerenal azotemia, making nephrotoxin avoidance even more critical 2