Benign transient hyperphosphatasia and HIV infection

Benign transient hyperphosphatasemia in infants and children: a retrospective database study

Benign transient hyperphosphatasemia is a condition characterized by greatly increased serum alkaline phosphatase (ALP) without laboratory or clinical evidence of underlying bone or liver disease. It is usually identified incidentally during routine blood testing. We describe the demographic and clinical characteristics of benign transient hyperphosphatasemia in a cohort of healthy infants and children. We performed a retrospective review of electronic medical records on all children aged 1 day to 18 years with a diagnosis of benign transient hyperphosphatasemia, who were registered at 3 central districts in Israel from January 1, 2000, to December 31, 2020. The demographic and clinical characteristics were retrieved from the medical files. The study group comprised 382 infants and children aged from 2 months to 14 years who had serum ALP > 1000 U/L (mean 2557 U/L, range 1002-14,589 U/L). The majority of participants (87%) were aged up to 24 months (median age 14 months, IQR 10-18 months). Fifty-four percent of the study participants were male. In many patients, there was a history of recent fever, gastroenteritis or diarrhea, acute otitis media, and viral infection. A seasonal peak was observed in autumn-early winter, but this may be a detection bias.

CONCLUSION

Benign transient hyperphosphatasemia seems to be a disorder described among otherwise healthy infants and children, which resolves spontaneously. Other known causes of markedly elevated serum ALP should be excluded, especially bone and liver disease. Higher awareness and recognition of this benign condition are important in order to avoid unnecessary tests and parental anxiety.

WHAT IS KNOWN

• Benign transient hyperphosphatasemia is a benign condition characterized by greatly increased serum alkaline phosphatase without laboratory or clinical evidence of underlying bone or liver disease, which usually resolves spontaneously, with no intervention.

WHAT IS NEW

• In the case of an incidental finding of high serum alkaline phosphatase in an otherwise healthy infant or child with no other clinical or laboratory suspicion of bone or liver disease, we recommend repeating the alkaline phosphatase level within a few months in order to confirm the resolution of this condition. • When benign transient hyperphosphatasemia is suspected, a "wait and see" approach is optimal in order to avoid unnecessary investigations and parental anxiety.

Rare Case of Benign Transient Hyperphosphatasemia in a Complicated Multiorgan Adult Transplant Patient: Case Report and Literature Review

BACKGROUND

Transient hyperphosphatasemia, characterized by isolated highly elevated alkaline phosphatase (ALP) activity in the absence of liver or bone disease, is typically seen in children but rarely in adults. Here we report highly elevated ALP activity in a complicated multiple-organ transplant patient due to benign transient hyperphosphatasemia.

CASE REPORT

A 54-year-old male had a complicated past medical history including a bilateral lung transplant for cystic fibrosis in 2006, colonic resection due to colon cancer in December 2011 and subsequent chemotherapy which ended in June 2022. He also had combined liver and kidney transplant in 2022 at our academic medical center. Post-transplant, he was treated with triple drug immunosuppressant therapy (tacrolimus, mycophenolic acid, and prednisone). Although his alkaline phosphatase (ALP) activity was 83 U/L, it continued to increase three months after combined liver and kidney transplant even though other liver enzymes were mildly elevated but total bilirubin remained within their reference ranges. Flecainide was discontinued but his ALP remained high, peaking at 5904 U/L. Finally, lansoprazole, ergocalciferol (vitamin D2) and vitamin E supplement were discontinued as nonessential medications, and coincidently ALP activity started to decline. Conclusions After ruling out all possibilities that may cause elevated ALP, we concluded that this is a rare case of benign transient hyperphosphatasemia in an adult transplant recipient.

A case series of benign transient hyperphosphatasemia from a pediatric endocrinology reference health facility in Turkey

Introduction

Benign transient hyperphosphatasemia (BTH), even a known condition, is not very well managed by primary care physicians. The diagnostic criteria for BTH were alkaline phosphatase (ALP) levels above 3-5 times greater than the age adjusted upper limit of normal among children under 5 years with no evidence of liver or bone disease whose ALP values resolved within 4 months.

Methods

This study involved 15 patients aged 0-5 years, who were referred to the pediatric endocrinology clinic for elevated ALP levels. They were diagnosed with BTH. We examined demographic and biochemical parameters including ALP and ALP isoenzymes, liver enzymes, calcium, phosphate, and parathormone (PTH) levels to rule out liver or bone disease as a cause for hyperphosphatasaemia.

Results

Of 15 patients 7 were male and 8 were female. Mean age was 2.45 ± 1.09 (range 1.2-4.6) years. Mean serum ALP level was 2315 ± 1028 IU/L (1102-4662), while liver enzymes, calcium, phosphate, PTH and vitamin D3 levels were in normal ranges. The mean normalization period of ALP was 2.4 ± 1.1 (0.5-4) months, and all were normal at the end of 4 months without any treatment.

Conclusion

This study and literature knowledge related to BTH has shown that being aware of BTH is very important for a primary care physician. Paediatricians can conveniently manage the differential diagnosis and follow up this period of elevated ALP.

Transient rise in alkaline phosphatase activity in adults

Benign transient hyperphosphatasia (BTH) is a condition that occurs mainly in infants and children and is characterised by a transient increase of serum alkaline phosphatase (ALP) activity up to several fold the adult upper reference limit (URL). The present report concerns BTH in 2 patients, aged 59 and 52 years old, who showed no evidence of bone or liver disease but had an increase in ALP activity up to 20-fold and 13-fold the adult URL, respectively. The diagnosis of BTH in the first case was made retrospectively, and after excluding liver and bone disease. However, in the second case the diagnosis was made early in the course of the disease, by performing an ALP isoenzyme electrophoresis test. Lengthy and extensive investigations were avoided in the second case. These cases highlight the occurrence of this condition in adulthood as well as in infancy and childhood.

Isoenzyme characterization in isolated elevation of alkaline phosphatase after liver transplantation in children

BACKGROUND

Isolated transient elevation of alkaline phosphatase (ALP) in the absence of bone or liver disease has been reported in children including liver transplant patients. Specific isoenzyme patterns have been associated with this phenomenon in healthy children but have not been reported after liver transplantation. The discovery of the isoenzyme pattern associated with benign transient hyperphosphatasemia in one child prompted a study of all our posttransplant patients.

METHODS

Retrospective analysis of ALP isoenzymes by polyacrylamide gel electrophoresis on banked serum samples.

RESULTS

The incidence of isolated transient hyperphosphatasemia was 4.3%. All 11 children demonstrated the isoenzyme pattern associated with benign transient hyperphosphatasemia. In one child, the hyperphosphatasemia occurred on a background of chronic cholangiopathy and in a second, shortly after an episode of probable cytomegalovirus hepatitis.

CONCLUSIONS

Isolated elevation of serum ALP after liver transplantation in children is common. Analysis of ALP isoenzymes, looking for the pattern of benign transient hyperphosphatasemia, can assist in the management of these children.