Intractable hypercalcaemia during pregnancy and the postpartum secondary to pathogenic variants in CYP24A1

SUMMARY: Parathyroid-independent hypercalcaemia of pregnancy, due to biallelic loss of function of the P450 enzyme CYP24A1, the principal inactivator of 1,25(OH)2D results in hypervitaminosis D, hypercalcaemia and hypercalciuria. We report two cases of this disorder, with intractable hypercalcaemia, one occurring during gestation and into the postpartum, and the other in the postpartum period. Case 1, a 47-year-old woman with a twin pregnancy conceived by embryo transfer, presented with hypercalcaemia at 23 weeks gestation with subnormal serum parathyroid hormone (PTH) and normal serum 25-OH D levels. She was admitted to hospital at 31 weeks gestation with pregnancy-induced hypertension, gestational diabetes and increasing hypercalcaemia. Caesarean section at 34 weeks gestation delivered two healthy females weighing 2.13 kg and 2.51 kg. At delivery, the patient's serum calcium level was 2.90 mmol/L. Postpartum severe hypercalcaemia was treated successfully with Denosumab 60 mg SCI, given on two occasions. CYP24A1 testing revealed she was compound heterozygous for pathogenic variants c.427_429delGAA, (p.Glu143del) and c.1186C>T, (p.Arg396Trp). Case 2, a 36-year-old woman presented 4 days after the delivery of healthy twins with dyspnoea, bradycardia, severe headaches, hypertension and generalized tonic-clonic seizures after an uneventful pregnancy. She was hypercalcaemic with a suppressed PTH, normal 25(OH)D, and elevated 1,25(OH)2D levels. Her symptoms partially responded to i.v. saline and corticosteroids in the short term but bisphosphonates such as Pamidronate and Zoledronic acid did not result in sustained improvement. Denosumab 120 mg SCI successfully treated the hypercalcaemia which resolved completely 2 months post-partum. CYP24A1 testing revealed she was homozygous for the pathogenic variant c.427_429delGAA, (p.Glu143del).

LEARNING POINTS: Hypercalcaemia in pregnancy can be associated with considerable morbidity with few options available for management. In non-PTH-related hypercalcaemia the diagnosis of CYP24A1 deficiency should be considered. Making a definitive diagnosis of CYP24A1 deficiency by genetic testing delays the diagnosis, while the availability of serum 24,25-dihydroxyvitamin D (24,25(OH)2D) will expedite a diagnosis. In pregnant women with CYP24A1 deficiency hypercalcaemia can worsen in the post-partum period and is more likely to occur with twin pregnancies but generally resolves within 2-3 months. Therapeutic alternatives are limited in pregnancy and their effectiveness is short-lived and mostly ineffective. Denosumab used in both our patients after delivery was the most effective agent normalizing calcium and may have benefit as a long-term therapeutic agent in preventing complications in patients with CYP24A1 deficiency.

Medienart:

E-Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:2019

Enthalten in:

Endocrinology, diabetes & metabolism case reports - 2019(2019) vom: 21. Nov.

Sprache:

Englisch

Beteiligte Personen:

Arnold, Nirusha [VerfasserIn]
O'Toole, Victor [VerfasserIn]
Huynh, Tien [VerfasserIn]
Smith, Howard C [VerfasserIn]
Luxford, Catherine [VerfasserIn]
Clifton-Bligh, Roderick [VerfasserIn]
Eastman, Creswell J [VerfasserIn]

Links:

Volltext

Themen:

1,25-dihydroxyvitamin-D
2019
25-hydroxyvitamin-D3
Albuminuria
Alpha-blockers
Australia
Bisphosphonates
Blood pressure
Bone
Bradycardia
Caesarean section
Calcium (serum)
Calcium (urine)
Corticosteroids
Denosumab
Dexamethasone
Dyspnoea
Fatigue
Female
Fluid repletion
Furosemide
Gestational diabetes mellitus
Glucocorticoids
Glucose tolerance
Gynaecology
Headache
Hydralazine*
Hypercalcaemia
Hypertension
Hypothyroidism
Insight into disease pathogenesis or mechanism of therapy
Journal Article
Kidney
Kidney stones
Labetalol
Levothyroxine
Magnesium*
Molecular genetic analysis
Nephrocalcinosis
Nephrolithiasis
Nephrology
November
PTH
PTH-related peptide*
Pamidronate
Parathyroid
Peripheral oedema
Polydipsia
Prednisone
Pregnancy
Pregnant adult
Saline
Seizures
Urology
Vitamin D
White
Zoledronic acid

Anmerkungen:

Date Revised 27.02.2024

published: Print-Electronic

Citation Status Publisher

doi:

10.1530/EDM-19-0114

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM30353947X