ABCD Syndrome: A Rare but Underrecognized Cause of Hypercalcemia in Down Syndrome
https://doi.org/10.15605/jafes.041.S1
- Author:
Nurul Farah Wahidah Abd Razak
1
;
Sze Teik Teoh
1
Author Information
1. Hospital Sultanah Bahiyah
- Publication Type:Journal Article
- MeSH:
ABCD syndrome;
Down Syndrome;
Hypercalcemia
- From:
Journal of the ASEAN Federation of Endocrine Societies
2026;41(S1):147-
- CountryPhilippines
- Language:English
-
Abstract:
Introduction:ABCD syndrome (ABnormal Calcium-CreatinineCalcinosis in Down syndrome) is a rare tetrad of hypercalcemia, hypercalciuria, nephrocalcinosis, and renal
impairment in children with Down syndrome, often with
delayed diagnosis resulting in irreversible renal damage.
We report a 7-year-old male with Down syndrome, who
previously had a stormy neonatal period due to large atrialseptal-defect and pulmonary hypertension, and required
surgery at 3-years-old with prior prolonged ventilation. He
was since bedbound with severe spastic diplegia, complicated by GERD and food aversion, requiring nasogastric tube feeding. He was discovered to have hypercalcemia
and renal impairment during admission in district hospital
for febrile illness with gastrointestinal symptoms. Initial
serum calcium was 2.78 mmol/L, phosphate 1.54 mmol/L,
magnesium 0.96 mmol/L, ALP 210 IU/L, urea 18.6 mmol/L,
and creatinine 266 umol/L. Renal impairment did not
improve and ultrasound KUB revealed bilateral small
kidneys with medullary nephrocalcinosis. Consultation
with the paediatric nephrologist concluded as CKDstage-4. He was transferred to our centre. He demonstrated
severe hypercalcemia (3.44 mmol/L), hypercalciuria (urinecalcium-to-creatinine-ratio of 1.17 mmol/mmol, >95 th%),
and suppressed iPTH (0.9 pmol/L,1.6–6.9), suggesting
PTH-independent process. 25-OH-Vit-D3 was 134 nmol/L
(74–250, sufficient). He was more irritable and moody,
but no seizures. ECG was normal. Skeletal assessment did
not reveal osteolytic changes or increased resorption. He
was investigated by paediatric hemato-oncologists, with
negative findings, despite extensive search for hematological or bone malignancy and granulomatous disease.
His ESR and immunoglobulin level was high for unknown
reasons. He was treated with intravenous and oral
hydration, dietary calcium restriction with modified lowcalcium formula, assisted by dietitian, and IV pamidronate
infusion (0.125 mg/kg) stat dose, resulting in stabilization of
serum calcium level (2.5 mmol/L), which persisted for about
8 weeks during follow-up.
Conclusion:ABCD syndrome should be considered in Down syndrome
children presenting with unexplained hypercalcemia. Early
recognition and intervention are vital.
- Full text:202608101735111785EP_P025.pdf
