Early elevated alkaline phosphatase increases the risk of large-for-gestational-age birth weight in pregnant women with normal glucose tolerance

Incidental Finding of Extreme Elevation of Serum Alkaline Phosphatase in Pregnancy

Increased levels of alkaline phosphatase (ALP) should alert us to changes in the liver, kidney, bone and malignancy. However, there is a physiological increase in pregnancy up to twice the upper limit. There has been a paucity of cases reporting extreme elevations of ALP in pregnancy. This is a case of an incidental pregnancy finding of a 24-fold increase in ALP in the third trimester (2877 U/L). The patient was kept under surveillance and ALP levels were monitored during the postpartum period.

Literature suggests a correlation between ALP elevation and several perinatal complications, proposing it could represent an important tool in monitoring high-risk pregnancies and underlying placental damage. We report a case with no perinatal complications and normal labor at term, with a placenta showing lesions of chronic villitis. We should not rely exclusively on an isolated, marked rise in ALP to dictate the approach in the absence of other fetomaternal considerations.

Extremely high levels of alkaline phosphatase and pregnancy outcome: case series and review of the literature

OBJECTIVES

To evaluate the association between extremely elevated alkaline phosphatase (ALKP) levels (above 1000 U/L) and adverse perinatal outcome.

METHODS

A retrospective case series of all parturients with extremely elevated ALKP levels taken throughout pregnancy at a single university-affiliated medical center (2010-2018). Demographics and medical data were retrieved. Following literature review, previously reported similar cases were added to the cohort. We report perinatal outcome of our cohort as well as literature review.

RESULTS

During study period 11 parturients with high ALKP were identified. Ten more cases were retrieved from PubMed search. Overall, median ALKP levels were 1880 (range 1052-4488 U/L). Reasons for evaluation were mostly nonspecific symptoms (pruritus, headache, abdominal pain) or routine obstetrical evaluation. In 10/12 (83%) cases, elevated ALKP levels were of placental origin; the rest had osteal origin. Median gestational age at delivery was 38 (range 35-41); four (19%) women had preterm delivery. Six patients (29%) had gestational diabetes mellitus and six (29%) had hypertensive disorders. Histopathology of the placenta was available in eight cases: three normal histology (38%) and five with different non-specific pathologies.

CONCLUSIONS

We report the largest case series of extremely elevated levels of ALKP in pregnancy thus far. Our data suggest association with adverse perinatal outcome.

Plasma Inorganic Pyrophosphate Deficiency Links Multiparity to Cardiovascular Disease Risk

Epidemiological studies indicate that elevated alkaline phosphatase activity is associated with increased cardiovascular disease risk. Other epidemiological data demonstrate that mothers giving multiple childbirths (multipara) are also at increased risk of developing late-onset cardiovascular disease. We hypothesized that these two associations stem from a common cause, the insufficient plasma level of the ectopic mineralization inhibitor inorganic pyrophosphate, which is a substrate of alkaline phosphatase. As alkaline phosphatase activity is elevated in pregnancy, we hypothesized that pyrophosphate concentrations decrease gestationally, potentially leading to increased maternal vascular calcification and cardiovascular disease risk in multipara. We investigated plasma pyrophosphate kinetics pre- and postpartum in sheep and at term in humans and demonstrated its shortage in pregnancy, mirroring alkaline phosphatase activity. Next, we tested whether multiparity is associated with increased vascular calcification in pseudoxanthoma elasticum patients, characterized by low intrinsic plasma pyrophosphate levels. We demonstrated that these patients had increased vascular calcification when they give birth multiple times. We propose that transient shortages of pyrophosphate during repeated pregnancies might contribute to vascular calcification and multiparity-associated cardiovascular disease risk threatening hundreds of millions of healthy women worldwide. Future trials are needed to assess if gestational pyrophosphate supplementation might be a suitable prophylactic treatment to mitigate maternal cardiovascular disease risk in multiparous women.

Extreme elevations of alkaline phosphatase in pregnancy: A case report

Background

The normal serum concentration of alkaline phosphatase (ALP) in adults over the age of 18 ranges from 37 to 116 U/L, while in pregnant women levels of up to twice that upper limit can still be normal. There have been very few reports of extreme elevations in ALP, and here we present the case of a 29-year-old pregnant woman with an incidentally found 30-fold increase.

Case

The patient, G6P2–1–2-4, received routine prenatal care, though presented to obstetric triage at 36 weeks and 1 day of gestation for diagnosis and management of viral rhinosinusitis and was found to have an ALP level of 2817 U/L. She was expectantly managed and levels were monitored during the peripartum period.

Conclusion

The literature proposes that elevation of the placental isotype of ALP could be a marker for placental insufficiency, preterm delivery, or infants born large for gestational age. We report a case with delivery of a normal infant and no placental pathology at term.

•

Increases in alkaline phosphatase in pregnancy are usually twice the upper limit of normal.

•

Elevations above normal are usually secondary to placental isotypes of the enzyme.

•

There is no accepted correlation between a high level of alkaline phosphatase and maternal or fetal pathology.