What are the recommendations for a 71-year-old patient with hyperglycemia, impaired renal function, proteinuria, trace occult blood in urine, and hypercalcemia who is scheduled for surgery?

Preoperative Management Recommendations for 71-Year-Old Patient with Multiple Metabolic Abnormalities

This patient requires optimization of renal function, glycemic control, and investigation of hypercalcemia before proceeding with elective surgery, as these abnormalities significantly increase perioperative morbidity and mortality risk.

Critical Preoperative Issues Requiring Attention

1. Impaired Renal Function (eGFR 40 mL/min/1.73m²)

• The presence of chronic kidney disease (CKD) Stage 3b with elevated creatinine (1.78 mg/dL) and BUN (44 mg/dL) represents an independent risk factor for perioperative cardiac complications and acute kidney injury 1.

• Preoperative creatinine >2 mg/dL is a significant independent risk factor for cardiac complications after major noncardiac surgery, and this patient approaches that threshold 1.

• Electrolyte and creatinine testing is indicated based on the patient's age >40 years, presence of hypertension (implied by renal disease), and chronic kidney disease 1.

• The elevated BUN/creatinine ratio (25) suggests a prerenal component that may be reversible with hydration 1.

• Perioperative hemodynamic optimization should target mean arterial pressure of 60-70 mmHg, or >70 mmHg if the patient is hypertensive, to maintain renal perfusion pressure 1.

2. Hyperglycemia (Glucose 128 mg/dL)

• The A1C goal for elective surgeries should be <8% whenever possible, and this must be measured preoperatively to evaluate long-term glycemic control 1, 2.

• The blood glucose goal in the perioperative period should be 100-180 mg/dL, with monitoring at least every 2-4 hours while NPO 1, 2.

• If the patient is on metformin, it should be held on the day of surgery only 1, 3.

• If the patient is on SGLT2 inhibitors, these must be discontinued 3-4 days before surgery to prevent life-threatening euglycemic diabetic ketoacidosis 1, 3.

• Other oral hypoglycemic agents should be held the morning of surgery 1, 3.

• Perioperative glycemic control in the range of 7.7-10 mmol/L (140-180 mg/dL) is recommended, preferably with a variable rate insulin infusion 1.

3. Proteinuria (2+) with Trace Occult Blood

• The combination of proteinuria and impaired renal function indicates chronic kidney disease with glomerular and/or tubular damage, which is a strong marker for progression of kidney disease and increased cardiovascular morbidity 4.

• Proteinuria in the setting of CKD increases the risk of perioperative acute kidney injury 4.

• Avoid nephrotoxic agents perioperatively, including NSAIDs and contrast agents if imaging is required 1.

• The trace occult blood combined with proteinuria suggests glomerular pathology requiring further investigation, but this should not delay urgent surgery 4.

4. Hypercalcemia (Calcium 10.4 mg/dL)

• Hypercalcemia associated with renal failure is indicative of underlying comorbidity (malignancy, hyperparathyroidism, multiple myeloma, sarcoidosis, or vitamin D intoxication) and requires investigation before elective surgery 5.

• Hypercalcemia can provoke or aggravate acute renal failure and must be corrected preoperatively 5.

• Treatment should include hydration and diuretics, with consideration of calcitonin if calcium levels are severely elevated 5.

• Renal function typically improves as serum calcium levels decrease 5.

5. Macrocytic Anemia (MCV 104 fL, Hemoglobin 12.9 g/dL)

• The hemoglobin of 12.9 g/dL is just below the normal range (13.0-17.7 g/dL) and represents mild anemia, which imposes stress on the cardiovascular system and may exacerbate myocardial ischemia 1.

• The elevated MCV (104 fL) and MCH (35.1 pg) suggest macrocytic anemia, potentially from B12/folate deficiency, hypothyroidism, or chronic kidney disease 1.

• Hematocrits <28% are associated with increased perioperative ischemia and complications, but this patient's hematocrit of 38.3% is acceptable for surgery 1.

Preoperative Optimization Algorithm

For Elective Surgery:

1. Delay surgery until the following are addressed:

   • Measure HbA1c; if >8%, optimize glycemic control before proceeding 1, 2
   • Investigate and treat hypercalcemia (PTH, vitamin D levels, imaging for malignancy) 5
   • Optimize volume status with hydration to improve prerenal azotemia 1
   • Evaluate macrocytic anemia (B12, folate, TSH) and treat if deficient 1

2. Medication adjustments:

   • Discontinue SGLT2 inhibitors 3-4 days before surgery 1, 3
   • Hold metformin on day of surgery 1, 3
   • Hold other oral hypoglycemics morning of surgery 1, 3
   • Adjust insulin dosing: give 75-80% of long-acting insulin or 50% of NPH dose 1, 2

3. Perioperative monitoring:

   • Blood glucose every 2-4 hours while NPO, targeting 100-180 mg/dL 1, 2
   • Consider arterial line for hemodynamic monitoring given renal dysfunction 1
   • Maintain MAP 60-70 mmHg (or >70 mmHg if hypertensive) 1
   • Avoid nephrotoxic agents 1

For Urgent/Emergency Surgery:

1. Proceed with surgery but implement aggressive perioperative management:
   • Variable rate insulin infusion targeting glucose 140-180 mg/dL 1
   • Aggressive hydration to optimize renal perfusion 1
   • Hemodynamic monitoring with arterial line 1
   • Treat hypercalcemia with IV fluids and diuretics 5

Common Pitfalls to Avoid

• Do not perform routine urinalysis in asymptomatic patients, but this patient's proteinuria and hematuria are clinically significant findings that require attention 1.

• Do not use NSAIDs for postoperative pain control given the renal dysfunction 1.

• Do not assume normal glucose control based on a single fasting glucose; HbA1c is essential for assessing long-term control 2.

• Do not overlook hypercalcemia as a benign finding; it requires investigation for underlying malignancy or other serious conditions 5.

• Avoid excessive diuresis that could worsen prerenal azotemia 1.

• Recognize that renal dysfunction increases the risk of hypoglycemia, requiring more frequent glucose monitoring 6.