Creatine Kinase (CK), Total — Serum
Typical CK levels are *lower* in pregnancy than in nonpregnant adults. Elevations may relate to muscle injury, labor, preeclampsia, HELLP, or autoimmune disease.
| Units | Nonpregnant Female | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| U/L | 39 – 238 | 27 – 83 | 25 – 75 | 13 – 101 |
Physiology in pregnancy
- CK levels often decrease due to hemodilution and reduced muscle enzyme leakage.
- Labor can cause temporary CK elevations.
- Marked elevations are *not* normal and warrant evaluation.
Causes of elevated CK in pregnancy
- Muscle injury, strenuous exercise
- Rhabdomyolysis (trauma, prolonged immobility, statins, illicit drugs)
- Preeclampsia / HELLP syndrome
- Myositis, autoimmune muscle disease
- Seizures
- Hypothyroidism
- Placental abruption associated muscle injury (rare)
- Intrapartum uterine hyperstimulation (mild elevation)
Causes of low CK
- Normal pregnancy dilutional effects
- Low muscle mass
- Connective tissue disorders causing reduced muscle mass
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009;114:1326–31.