Table 3.
Relationship between adult Reference Intervals and Decision Limits for three laboratory tests
| GLUCOSE (fasting plasma) | |||
| Reference | 70 – 115 mg/dL | (28) | |
| Intervals Adults | (3.9 – 6.4 mmol/L) | ||
| Decision Limits | Hypoglycemia | 55 – 70 mg/dL (3.0 – 3.9 mmol/L) |
Possible impairment of cognitive function |
| Life-threatening hypoglycemia | ≤40-55 mg/dL (≤ 2.2-3.0 mmol/L) |
Neurological symptoms (22,25) | |
Hyperglycemia
|
100 – 125 mg/dL (5.5-6.95 mmol/L) |
Impaired fasting glucose (29) | |
| ≥ 126 mg/dL (≥ 7.0 mmol/L) |
(29) | ||
| CALCIUM (total) | |||
| Reference | 8.8 – 10.6 mg/dL | (31) | |
| Intervals Adults | (2.20 – 2.65 mmol/L) | ||
| Decision Limits | Mild Hypocalcemia | < 8.0 mg/dL (2.0 mmol/L) |
Associated with risk of convulsion |
| Hypocalcemic crisis | < 6.0 – 7.0 mg/dL (< 1.50 – 1.75 mmol/L) |
(22,32) | |
| Mild Hypercalcemia | <12 mg/dL (<3.0 mmol/L) |
Associated with primary hyperparathyroidism etc… | |
| Hypercalcemic crisis | ≥ 12.0-14.0 mg/dL (3.0-3.5 mmol/L) |
Associated with other symptoms. Most common causes are hyperparathyroidism and tumor associated hypercalcemia (22) | |
| POTASSIUM (heparin plasma) | |||
| Reference | 3.6 – 4.8 mmol/L | (33) | |
| Intervals Adults Decision Limits | Hypokalemia | 3.0 – 3.5 mmol/L | If normal cardiac function, generally does not cause any cardiac problems |
| Life-threatening Hypokalemia | < 2.5 – 3.0 mmol/L | Causes clinical symptoms; May be associated with cardiac arrhythmia (22) | |
| Hyperkalemia | ≥ 5 mmol/L | Sign that the regulatory mechanism for potassium balance is failing. Cardiovascular and neuromuscular symptoms (22) | |
| Life-threatening Hyperkalemia | ≥ 6.0-6.5 mmol/L | ||