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 isolated hyperparathyroidism


Other Names:
Hyperparathyroidism 1; HRPT1; Hyperparathyroidism, familial isolated primary; Hyperparathyroidism 1; HRPT1; Hyperparathyroidism, familial isolated primary; FIHP; Familial primary hyperparathyroidism See More
Familial isolated hyperparathyroidism (FIHP) is an inherited form of primary hyperparathyroidism that is not associated with other features.[1] The age of diagnosis varies from childhood to adulthood. In FIHP, tumors involving the parathyroid glands cause the production and release of excess parathyroid hormone, which in turn causes increased calcium in the blood (hypercalcemia). The tumors are usually benign, but a cancerous tumor can develop in rare cases. Abnormal levels of calcium cause many of the symptoms of FIHP, including kidney stones, nausea, vomiting, high blood pressure (hypertension), weakness, and fatigue. Osteoporosis often also develops. FIHP may be caused by mutations in the MEN1, CDC73 (also known as the HRPT2 gene), or CASR genes and is typically inherited in an autosomal dominant manner. In some cases, the cause is unknown. Mutations in the MEN1 and CDC73 genes cause other conditions in which hyperparathyroidism is one of many features, but some people with mutations in these genes have only isolated hyperparathyroidism. FIHP can also represent an early stage of other syndromes.[2] Treatment for FIHP often includes surgical removal of the affected gland(s).[3]
Last updated: 12/22/2014

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
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance 0000006
Hypercalcemia
High blood calcium levels
Increased calcium in blood
[ more ] 		0003072
Primary hyperparathyroidism 0008200
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Last updated: 7/1/2020
Familial isolated hyperparathyroidism (FIHP) is typically inherited in an autosomal dominant manner.[2] This means that having only one changed (mutated) copy of the responsible gene in each cell is enough to cause signs or symptoms of the condition. When a person with an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit the mutated copy of the gene from the affected parent.
Last updated: 12/23/2014
The diagnosis of familial isolated hyperparathyroidism (FIHP) is primarily a diagnosis of exclusion. This means that it is diagnosed when no symptoms or genetic features of other forms of familial hyperparathyroidism are present. FIHP may be the only feature of another condition that is not manifesting completely, or it may be a distinct condition due to mutations in genes that have not yet been identified. Clinical exams, laboratory tests, and histological (microscopic) findings are needed before making a diagnosis of FIHP.[4]

A diagnosis of FIHP may include the findings of:

In the majority of people with FIHP, genetic mutations are not found. However, in some people, mutations in
the MEN1, CASR, and CDC73 (HRPT2) genes have been reported. At this time, no gene has been associated exclusively with FIHP.[4]

Last updated: 12/23/2014

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

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 isolated hyperparathyroidism. 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.

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

  • The Assistance Fund provides various services, including education and financial aid, to help patients with a chronic or serious illness cover the cost of FDA-approved medications. Patients must be U.S citizens or permanent residents.

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.

Where to Start

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • 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) 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 isolated hyperparathyroidism. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My sister has been diagnosed with primary hyperparathyroidism and has many serious symptoms of the disorder. She is scheduled for surgery. What are the chances that I also have familial isolated hyperparathyroidism? I have at least 9 strong symptoms of the disorder: fatigue, serious sleep problems, GERD, hair loss, frequent palpitations, hypertension, memory issues, major depression, and severe constipation. I usually have serum calcium in the low to mid 10s, sometimes higher. See answer


  1. Thereasa A Rich, Mimi I Hu, Jack W Martin, Nancy D Perrier, and Steven G Waguespack. CDC73-Related Disorders. GeneReviews. May 24, 2012; http://www.ncbi.nlm.nih.gov/books/NBK3789/. Accessed 12/22/2014.
  2. Familial isolated hyperparathyroidism. Genetics Home Reference. August, 2012; http://ghr.nlm.nih.gov/condition/familial-isolated-hyperparathyroidism. Accessed 12/22/2014.
  3. Lawrence Kim. Hyperparathyroidism. Medscape. April 28, 2014; http://emedicine.medscape.com/article/127351-overview#aw2aab6b4. Accessed 12/22/2014.
  4. Pontikides N, et. al. Genetic basis of familial isolated hyperparathyroidism: a case series and a narrative review of the literature. J Bone Miner Metab. July 2014; 32(4):351-366.