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Familial Hypocalciuric Hypercalcemia (FHH)

Autosomal-dominant lifelong mild hypercalcemia from CASR mutation, with low urinary calcium and no organ damage.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Endokrinoloji department. Book Appointment →

What is Familial Hypocalciuric Hypercalcemia (FHH)?

Familial hypocalciuric hypercalcemia (FHH) is an autosomal-dominant cause of mild lifelong hypercalcemia caused most often by inactivating mutations in CASR (calcium-sensing receptor) — also AP2S1 and GNA11 — that reset the calcium set-point upward.

Patients are usually asymptomatic with mildly elevated calcium, slightly elevated or inappropriately normal PTH, and inappropriately low urinary calcium with calcium-creatinine clearance ratio less than 0.01.

FHH must be distinguished from primary hyperparathyroidism, because parathyroidectomy does not correct it. Diagnosis is confirmed by genetic testing in atypical or severe cases.

Symptoms

Mild persistent hypercalcemia (10.5-11.5 mg/dL)
Usually asymptomatic — lab finding
No history of kidney stones
No fragility fractures
Family history of hypercalcemia
Normal cognition and well-being
Pancreatitis very rare

Risk Factors

Heterozygous CASR mutation (autosomal dominant)
AP2S1 or GNA11 mutation (rarer subtypes)
Family history of mild hypercalcemia
Family history without nephrolithiasis or osteoporosis
Lithium use can confound diagnosis
Vitamin D deficiency can mask the picture

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Persistent mild hypercalcemia
  • Family history of hypercalcemia
  • Distinguishing from primary hyperparathyroidism
  • Before considering parathyroidectomy
  • Family screening counseling
  • Severe symptoms (atypical FHH)
  • Pregnancy planning with FHH

Treatment Methods

01
No specific treatment in classic asymptomatic FHH
02
Avoid parathyroidectomy (does not normalize calcium)
03
Family screening and genetic counseling
04
Cinacalcet in atypical/severe FHH
05
Optimize vitamin D and hydration
06
Monitor renal function and bone density
07
Avoid lithium and thiazides if possible

Which Department to Visit?

You can visit our Endokrinoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.