National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Familial hypocalciuric hypercalcemia


Other Names:
Familial benign hypercalcemia; FBH; FBHH; Familial benign hypercalcemia; FBH; FBHH; FHH See More
Subtypes:
Familial hypocalciuric hypercalcemia (FHH) is an inherited disorder that causes abnormally high levels of calcium in the blood (hypercalcemia) and low to moderate levels of calcium in urine (hypocalciuric). People with FHH usually do not have any symptoms and are often diagnosed by chance during routine bloodwork. Weakness, fatigue, issues with concentration, and excessive thirst (polydipsia) have been reported by some people with FHH. Rarely, people with this disorder experience inflammation of the pancreas (pancreatitis) or a buildup of calcium in the joints (chondrocalcinosis).[1][2]

FHH is mainly classified into three different types depending on the genetic cause. FHH type 1 is the most common type of FHH and is caused by changes (also known as pathogenic variants or mutations) in the CASR gene. The protein made from the CaSR gene, the calcium-sensing receptor (CaSR protein), monitors and regulates the level of calcium in the blood. FHH type 2 is caused by changes in the GNA11 gene, and FHH type 3 is caused by changes in the AP2S1 gene. All three types of FHH are inherited in an autosomal dominant manner. In rare cases, FHH may be caused when a person's immune system mistakenly makes antibodies that attack the CaSR protein. The autoimmune form of FHH is not known to be caused by changes in a specific gene.[1][2][3]

Diagnosis of FHH is suspected by high levels of calcium in the blood, especially when there are no other symptoms present. Further blood and urine tests may be used to rule out other possible causes. Genetic testing can confirm the diagnosis of FHH, except in rare autoimmune cases.[2][4] Treatment is typically considered unnecessary because most people with FHH do not have symptoms. If pancreatitis occurs, removal of the parathyroid gland (parathyroidectomy) may be recommended.[1][2]
Last updated: 7/11/2018
While most people with familial hypocalciuric hypercalcemia (FHH) do not have symptoms, associated symptoms may include:[1][2][3]

Rarely, adults with FHH may experience recurring inflammation of the pancreas (pancreatitis), a build-up of calcium crystals in certain joints of the body (chondrocalcinosis), and a build-up of calcium in the veins (vascular calcification).[1]

Last updated: 7/11/2018

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
100% of people have these symptoms
Hypocalciuria
Low urine calcium levels
0003127
80%-99% of people have these symptoms
Parathormone-independent increased renal tubular calcium reabsorption 0003529
Reduced ratio of renal calcium clearance to creatinine clearance
Reduced ration of kidney calcium clearance to creatinine clearance
0003513
30%-79% of people have these symptoms
Infantile hypercalcemia 0008250
Osteomalacia
Softening of the bones
0002749
Renal hypophosphatemia 0008732
5%-29% of people have these symptoms
Chondrocalcinosis
Calcium deposits in joints
0000934
Episodic abdominal pain 0002574
Fatigue
Tired
Tiredness
[ more ] 		0012378
Headache
Headaches
0002315
Hypermagnesemia
High blood magnesium levels
0002918
Hypomagnesiuria
Decreased urine magnesium
Low urine magnesium levels
[ more ] 		0012609
Nausea and vomiting 0002017
Peptic ulcer
Sore in the lining of gastrointestinal tract
0004398
1%-4% of people have these symptoms
Autoimmunity
Autoimmune disease
Autoimmune disorder
[ more ] 		0002960
Hypocalcemic seizures
Low calcium seizures
0002199
Lipoma
Fatty lump
Noncancerous fatty lump
[ more ] 		0012032
Nephrolithiasis
Kidney stones
0000787
Pancreatitis
Pancreatic inflammation
0001733
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Last updated: 7/1/2020
A person with familial hypocalciuric hypercalcemia (FHH) has a 50% (1 in 2) risk to pass on the genetic change (pathogenic variant, also called mutation) to each of his/her children.[1][2] This is known as autosomal dominant inheritance. People have two copies of each gene (one inherited from each parent). For FHH, one copy of the gene with the pathogenic variant in each cell is sufficient to cause the disorder. The copy of the gene with the pathogenic variant may be inherited from an affected parent, or it may occur for the first time in the person with the disorder. 

Rarely, a person may inherit a pathogenic variants in both copies of one of the genes associated with FHH. This can lead to a severe form of the disorder called neonatal severe primary hyperparathyroidism (NSHPT). This disorder may become evident within the first week of life and can be life-threatening. NSHPT is usually caused by pathogenic variants in both copies of the CASR gene.[3]

Last updated: 7/11/2018

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Primary hyperparathyroidism is clinically similar to FHH, apart from the presence of hypercalcemia. Other differential diagnoses include humoral malignant hypercalcemia and sarcoidosis (see this term).
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Familial hypocalciuric hypercalcemia. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) lists the subtypes and associated genes for Familial hypocalciuric hypercalcemia in a table called Phenotypic Series. Each entry in OMIM includes a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
  • !LINK! is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Familial hypocalciuric hypercalcemia. Click on the link to view a sample search on this topic.

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  1. Lienhardt-Roussie A. Familial hypocalciuric hypercalcemia. Orphanet. May 2014; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=405.
  2. Afzal M, Kathuria P. Familial Hypocalciuric Hypercalcemia (FHH). StatPearls [Internet]. StatPearls Publishing; January 2018; https://www.ncbi.nlm.nih.gov/books/NBK459190/.
  3. Stokes VJ, Nielsen MF, Hannan FM, Thakker RV. Hypercalcemic Disorders in Children. Journal of Bone and Mineral Research. November 2017; 32(11):2157-2170. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5703166/.
  4. Christensen SE1, Nissen PH, Vestergaard P, Mosekilde L. Familial hypocalciuric hypercalcaemia: a review. Curr Opin Endocrinol Diabetes Obes. December 18, 2011; 18(6):359-70. https://www.ncbi.nlm.nih.gov/pubmed/21986511.