| Adrenocorticotropic hormone (ACTH) stimulation test (cosyntropin test): 0.25 mg of synthetic ACTH1-24 (cosyntropin) is administered IV or IM, and serum cortisol is measured at 0, 30, and 60 min. Normal response: peak cortisol >20 μg/dL (>540 nmol/L). A dose of 1 μg of ACTH will give a similar response in the normal individual (see Chapter 9). |
| ACTH | Plasma | <3 y 3-17 y >18 y | Not established 9-57 ng/L 6-50 ng/L | 0.222 | – 2-12.7 pmol/L 1.3-11 pmol/L | Collect in silicone-coated EDTA-containing tubes. Keep iced. Avoid contact with glass during collection and separation. Process immediately. Separate and freeze plasma in plastic tube at –20°C. |
| Aldosterone | Serum (fasting) | >18 y Upright 8:00-10:00 AM Upright 4:00-6:00 PM Supine 8:00-10:00 AM Pediatric 1-12 mo 1-4 y 5-9 y 10-13 y 14-17 y Premature Infants (31-35 wk) Term Infants | <28 ng/dL <21 ng/dL 3-16 ng/dL 2-70 ng/dL 2-37 ng/dL <9 ng/dL <21 ng/dL <35 mgdL <144 ng/dL <217 ng/dL | 27.7 | <776 pmol/L <582 pmol/L 83.1-443 pmol/L 55.4-1939 pmol/L 55.4-1025 pmol/L <243 pmol/L 582 pmol/L 970 pmol/L 3989 pmol/L 6011 pmol/L | Levels in pregnant patients are three to four times higher. |
| Urine | Sodium diet (100-300 mmol/d) Children: 2-7 y 8-11 y 12-16 y Adult Post-fludrocortisone or intravenous saline infusion | ≤5.7 μg/d ≤10.2 μg/d ≤15.6 μg/d ≤2.3-21 μg/d ≤5.0 μg/d | – | – | Collect 24-h specimen in 10 g boric acid to maintain pH ≤7.5. Refrigerate during collection. |
| Alkaline phosphatase, bone specific | Serum | 2-24 mo 6-9 y 10-13 y Males Females 14-17 y Males Females Adult males 18-29 y 30-39 y 40-49 y 60-68 y Adult females 18-29 y 30-39 y 40-49 y 50-76 y | 25.4-124.0 μg/L 41-134.6 μg/L 43.8-177.4 μg/L 24.2-154.2 μg/L 13.7-128 μg/L 10.5-75.2 μg/L 8.4-29.3 μg/L 7.7-21.3 μg/L 7.0-18.3 μg/L 7.6-14.9 μg/L 4.7-17.8 μg/L 5.3-19.5 μg/L 5.0-18.8 μg/L 5.6-29 μg/L | – | – | IRMA; collect following an overnight fast; useful in Paget disease and osteoporosis; assay also known as Ostase; increased levels seen in states of high bone turnover (Paget disease, hyperthyroidism, osteoporosis). |
| Alpha subunit | Serum | Men Women Premenopausal Postmenopausal Hypothyroid Pregnant or hCG-producing tumor | ≤0.6 ng/mL ≤1.5 ng/mL 0.9-3.3 ng/mL ≤3.7 ng/mL 1.8-360 ng/mL | – | – | RIA; used to assess gonadotropin hormone subunit secretion in pituitary adenomas. |
| 3α-Androstanediol glucuronide | Serum | Prepubertal children Tanner Stages II-III Male Female Adult Male Female | 0.1-0.6 ng/mL 0.19-1.64 ng/mL 0.33-2.44 ng/mL 2.6-15 ng/mL 0.6-3.0 ng/mL | 2.14 | 0.2-1.3 nmol/L 0.41-3.51 nmol/L 0.71-5.22 nmol/L 5.6-32.1 nmol/L 1.3-6.4 nmol/L | Freeze serum and store at –20°C. |
| Androstenedione | Serum | Men 18-30 y 31-50 y 51-60 y Women Follicular Midcycle Luteal Postmenopausal Children 1-12 mo 1-4 y 5-9 y 10-13 y 14-17 y Premature infants (31-35 wk) Term Infants Tanner II-III Male Female Tanner IV-V Male Female | 50-220 ng/dL 40-190 ng/dL 50-220 ng/dL 35-250 ng/dL 60-285 ng/dL 30-235 ng/dL 20-75 ng/dL 6-78 ng/dL 5-51 ng/dL 6-115 ... |