Related Experiment Video
Updated: Jun 21, 2026
Skeletal Phenotype Analysis of a Conditional Stat3 Deletion Mouse Model
Published on: July 3, 2020
High frequencies of elevated alkaline phosphatase activity and rickets exist in extremely low birth weight infants
Shannon M Mitchell1, Stefanie P Rogers, Penni D Hicks
1Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA. ShannonMitch@gmail.com
Insights
Extremely low birth weight infants often develop osteopenia and rickets. Lower birth weight is linked to higher alkaline phosphatase activity and increased rickets risk, suggesting early screening and supplementation are crucial.
Area of Science:
- Neonatalogy
- Pediatric Endocrinology
- Nutritional Science
Background:
- Osteopenia and rickets are prevalent in extremely low birth weight (ELBW) infants despite standard supplementation.
- Limited data exist on mineral status markers in this vulnerable population.
- This study investigates the relationship between birth weight and rickets markers in ELBW infants.
Purpose of the Study:
- To determine the relationship between birth weight (BW) and peak serum alkaline phosphatase activity (P-APA) in ELBW infants.
- To evaluate the diagnostic experience of rickets in ELBW infants.
- To identify risk factors for osteopenia and rickets in ELBW infants.
Main Methods:
- Retrospective review of 113 ELBW infants admitted to Texas Children's Hospital NICU (2006-2007).
- Analysis of peak serum alkaline phosphatase activity (P-APA) and its correlation with birth weight, gestational age, and serum phosphorus.
- Radiographic evaluation of 32 infants for rickets and osteopenia, with radiologist review masked to laboratory values.
Main Results:
- A significant inverse relationship was observed between birth weight and P-APA in ELBW infants.
- Infants with lower birth weight (<600 g and 600-800 g) exhibited significantly higher P-APA levels compared to those 800-1000 g.
- Infants weighing <600 g had a higher incidence of radiologic rickets (10/20) compared to heavier infants.
Conclusions:
- Elevated P-APA (>600 IU/L) is common in ELBW infants, with lower birth weight being a significant risk factor for both elevated P-APA and radiologic rickets.
- No specific P-APA threshold reliably predicted radiologic rickets.
- Early screening and mineral supplementation, particularly for infants <600 g, are recommended due to the high risk of osteopenia and rickets.
Background:
Osteopenia and rickets are common among extremely low birth weight infants (ELBW, <1000 g birth weight) despite current practices of vitamin and mineral supplementation. Few data are available evaluating the usual course of markers of mineral status in this population. Our objectives in this study were to determine the relationship between birth weight (BW) and peak serum alkaline phosphatase activity (P-APA) in ELBW infants and evaluate our experience with the diagnosis of rickets in these infants.
Methods:
We evaluated all ELBW infants admitted to Texas Children's Hospital NICU in 2006 and 2007. Of 211 admissions, we excluded 98 patients who were admitted at >30 days of age or did not survive/stay for >6 weeks. Bone radiographs obtained in 32 infants were reviewed by a radiologist masked to laboratory values.
Results:
In this cohort of 113 infants, P-APA was found to have a significant inverse relationship with BW, gestational age and serum phosphorus. In paired comparisons, P-APA of infants <600 g (957 +/- 346 IU/L, n = 20) and infants 600-800 g (808 +/- 323 IU/L, n = 43) were both significantly higher than P-APA of infants 800-1000 g (615 +/- 252 IU/L, n = 50), p < 0.01. Thirty-two patients had radiographic evaluation for evidence of rickets, based on P-APA greater than 800 IU/L, parenteral nutrition greater than 3 to 4 weeks, or clinical suspicion. Of these, 18 showed radiologic rickets and 14 showed osteopenia without rickets. Infants with BW <600 g were more likely to have radiologic rickets (10/20 infants) compared to those with BW 600-800 g (6/43 infants) and BW 800-1000 g (2/50 infants), p < 0.01 for each. P-APA was not significantly higher in infants with radiologic rickets (1078 +/- 356 IU/L) compared to those without radiologic evidence of rickets (943 +/- 346, p = 0.18).
Conclusion:
Elevation of P-APA >600 IU/L was very common in ELBW infants. BW was significantly inversely related to both P-APA and radiologic rickets. No single value of P-APA was related to radiological findings of rickets. Given the very high risk of osteopenia and rickets among ELBW infants, we recommend consideration of early screening and early mineral supplementation, especially among infants <600 g BW.
Related Concept Videos
01:33Introduction to Electrolytes
Role of Sodium
One...
01:29Bone Disorders
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
01:27Roles of Electrolytes: Calcium and Phosphate
The calcium concentration in blood plasma is primarily regulated...
01:25Role of Vitamins in Maintaining Bone Health
Vitamin A
Vitamin A is involved in the process of bone remodeling. Retinoic acid, the active metabolite of Vitamin A, has nuclear receptors in osteoblasts and osteoclasts, which are involved in bone remodeling.
Vitamin B12
Vitamin B12 acts as a cofactor during the formation of osteoblast-related proteins, such as osteocalcin. Vitamin B12 plays a role...
01:24Pharmacokinetics in Pediatric Patients: Drug Metabolism
01:23Pharmacokinetics in Pediatric Patients: Overview and Drug Absorption