3.6
Preoperative Labs
- Preoperative testing is overused for those undergoing low‐risk, ambulatory surgery [11]
- The below lab value ranges for “normal” can vary between institution and “ideal” lab values are patient and scenario specific
Blood Glucose
- Normal blood glucose (70–140 mg/dl)
- Depends on current fasting state and age
- Children, both with and without diabetes, will have higher blood glucose levels
| Hypoglycemia | Prolonged fasting Malnourishment Insulinoma Exogenous insulin Oral hypoglycemics |
| Hyperglycemia | Diabetic/Prediabetic Morbid obesity Stress Surgery Illness Withholding hypoglycemic agents Glucocorticoids |
Hemoglobin A1c (HbA1c)
- The percent of glucose bound (glycosylated) to hemoglobin
- Results valid for ~3–4 months as that is the lifespan of the RBC
- Recent blood transfusion can distort results
- Adults
- Normal: <5.7%
- Prediabetes: 5.7–6.4%
- Diabetic: >6.5%
- Pediatrics
- Normal: <5.7%
- Target for NIIDM: <7%
- Target for IDDM: <7.5%
| HbA1c (%) | Average blood glucose (mg/dl) | Average blood glucose (mmol/l) |
|---|---|---|
| 7 | 154 | 8.6 |
| 8 | 183 | 10.1 |
| 9 | 212 | 11.8 |
| 10 | 240 | 13.4 |
Basic Metabolic Panel (BMP) (Figure 3.11)
| Hypernatremia | Hypovolemia Diabetes insipidus |
| Hyponatremia | Hypovolemia Malnourishment Alcoholism Diuretics CHF CKD ESRD |
| Hyperkalemia | ESRD Addison’s Disease Rhabdomyolysis Digoxin ACEi ARBs |
| Hypokalemia | Sweating Hypomagnesemia Emesis Diarrhea Antiretrovirals |
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