Diagnosis and Treatment
This patient has severe hyperglycemia (glucose 402 mg/dL) requiring immediate insulin therapy, with concurrent evaluation needed for the elevated calcium and liver enzymes to rule out underlying malignancy or other serious conditions.
Primary Diagnosis: Uncontrolled Diabetes Mellitus
Immediate Treatment Approach
Insulin therapy must be initiated immediately because this patient meets criteria for severe hyperglycemia with a glucose of 402 mg/dL, which exceeds the threshold of 300-350 mg/dL that mandates insulin initiation 1. The American Diabetes Association guidelines specify that when blood glucose levels are 300-350 mg/dL or greater, basal insulin plus mealtime insulin is the preferred initial regimen, especially if symptomatic or catabolic features are present 1.
Insulin Dosing Protocol
- Start basal insulin at 10 units or 0.1-0.2 units/kg of body weight 1
- Add rapid-acting mealtime insulin (lispro, aspart, or glulisine) administered immediately before meals if symptomatic 1
- Timely dose titration based on self-monitoring blood glucose levels is critical 1
Why Metformin Should NOT Be Started Now
Metformin is contraindicated in this acute setting due to the elevated BUN of 29 mg/dL indicating renal impairment 2. Metformin should be suspended during hospitalization if renal function deteriorates, and it requires verification that eGFR is ≥30 mL/min/1.73 m² before initiation 2. With a BUN of 29, renal function must be fully assessed before considering metformin 2.
Critical Secondary Concerns Requiring Urgent Evaluation
Hypercalcemia Assessment
The calcium of 10.6 mg/dL is at the upper limit of normal but requires careful interpretation:
- Check ionized calcium immediately to confirm true hypercalcemia, as total calcium can be misleading 3
- Measure intact parathyroid hormone (PTH) to differentiate parathyroid-mediated from non-parathyroid causes 4, 3
- The combination of renal impairment (BUN 29) with borderline elevated calcium raises concern for hypercalcemia-induced acute kidney injury, which can occur when calcium exceeds 13-15 mg/dL but may contribute to renal dysfunction at lower levels 3
Malignancy Screening
The constellation of hyperglycemia, hypercalcemia, elevated liver enzymes (ALT 46), and renal impairment mandates evaluation for underlying malignancy 3:
- Multiple myeloma can present with this exact tetrad of findings 3
- Obtain complete blood count, serum protein electrophoresis, and imaging to exclude hematologic or solid organ malignancy 3
- Hypercalcemia associated with acute renal failure is indicative of comorbidity in virtually all cases 3
Hepatic Dysfunction Evaluation
The ALT of 46 U/L (mildly elevated) requires investigation:
- Advanced chronic liver disease can cause hypercalcemia, particularly with concurrent renal insufficiency 4
- Check total bilirubin, prothrombin time, and albumin to assess hepatic synthetic function 4
- Hypercalcemia in liver disease is typically non-parathyroid mediated with suppressed PTH 4
Treatment Algorithm
Step 1: Immediate Management (First 24-48 Hours)
- Initiate basal insulin at 10 units or 0.1-0.2 units/kg 1
- Add rapid-acting insulin before meals if symptomatic 1
- Aggressive IV hydration with normal saline to address both hyperglycemia and potential hypercalcemia 3
- Monitor for diabetic ketoacidosis (check beta-hydroxybutyrate or urine ketones) 1
Step 2: Diagnostic Workup (Within 24 Hours)
- Comprehensive metabolic panel with eGFR calculation 2
- Ionized calcium and intact PTH 4, 3
- HbA1c to assess chronic glycemic control 1
- Complete blood count, serum protein electrophoresis 3
- Hepatic function panel including bilirubin, albumin, PT/INR 4
- 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels 4
Step 3: Transition Planning (After 48-72 Hours)
Once glucose is controlled and diagnostic workup complete:
- If eGFR ≥45 mL/min/1.73 m² and no contraindications exist, add metformin 500 mg once daily with dinner 2
- Continue basal insulin and titrate based on fasting glucose 1
- Consider adding oral agents after symptoms resolve and glucose levels decrease 1
Critical Pitfalls to Avoid
- Never delay insulin in severe hyperglycemia (>300 mg/dL) - this is the most common error and increases risk of diabetic ketoacidosis 1
- Never start metformin without confirming adequate renal function (eGFR ≥30 mL/min/1.73 m²) 2
- Never attribute hypercalcemia solely to laboratory error - always confirm with ionized calcium and investigate underlying causes 3
- Never miss occult malignancy - the combination of these laboratory abnormalities demands thorough evaluation 3
- Beware of rapid correction of hypernatremia if osmotic diuresis from glycosuria has occurred, as this can lead to severe electrolyte disturbances 5