Primary Hyperparathyroidism (PHPT) During Pregnancy

Prevalence of PHPT during pregnancy:
- Is reported to be between 0.15% and 1.4%
PHPT during pregnancy may have serious consequences to the mother and to the fetus:
- If it remains unrecognized or untreated:
  - In up to 80% of patients, it is not recognized due to physiological changes during pregnancy that mask gestational PHPT, such as:
    - Hemodilution:
      - Related to intravascular fluid expansion
    - Hypoalbuminemia
    - Increased glomerular filtration rate:
      - Resulting in hypercalciuria
    - Transplacental transfer of calcium
- Clinical presentation of PHPT durign pregnagncy may range from:
  - Hyperemesis, lethargy, hypertension, thirst, abdominal pain, depression, constipation, bone fracture, maternal heart rhythm disorders, maternal hypertension to preeclampsia, nephrolithiasis, pancreatitis, hyperemesis gravidarum, and hypercalcemic crisis:
    - Because the understanding of this concept and standard monitoring of all pregnant patients in developed countries:
      - The presentation of PHPT during pregnancy is very mild:
        
        It is diagnosed in earlier stages
- Sestamibi scan is contraindicated during pregnancy:
  - Due to radiation exposure risk to the fetus:
    - Ultrasound is the only diagnostic option since it carries no risk of radiation exposure and is easy to perform
- Management of PHPT during pregnancy:
  - Should be individualized based on symptoms and severity of hypercalcemia:
    - Parathyroidectomy is indicated in symptomatic patients and patients with severe hypercalcemia:
      - When calcium level is elevated above 11 mg/dL (2.74 mmol/L)
    - Parathyroidectomy should be performed only in the second trimester:
      - To prevent miscarriage and anesthetic drugs exposure in the first trimester or spontaneous delivery in the third trimester
    - Mild form of PHPT causes low risk of maternal and obstetrical complications:
      - Therefore the patients can be managed conservatively, and parathyroidectomy can be deferred until after the delivery
    - Some medications, such as bisphosphonates, are contraindicated during pregnancy
    - Calcitonin:
      - Showed limited data and poor effectiveness:
        
        But it does not cross the placenta and appears to be safe
    - Cinacalcet:
      - Has shown good results in several studies:
        
        Although safety data are limited
    - Recent paper published by Rigg et al. retrospectively reviewed data of 28 pregnant patients with PHPT (22 managed medically and 6 surgically by elective parathyroidectomies):
      - Showed that 30% of those who were managed medically developed preeclampsia, and 66% managed medically had preterm deliveries