Pseudohypoparathyroidism

Causes

The parathyroid glands produce parathyroid hormone, or PTH. PTH helps control calcium, phosphorus, and vitamin D levels within the blood and bone.

If you have pseudohypoparathyroidism, your body produces the right amount of PTH, but is "resistant" to its
effect. This causes low blood calcium levels and high blood phosphate levels.

Pseudohypoparathyroidism is caused by abnormal genes. There are different types of pseudohypoparathyroidism.
All forms of are rare.

• Type Ia is inherited in an autosomal dominant manner. That means only one parent needs to pass you the faulty gene in for you to have the condition. The condition causes short stature, round face, and short hand bones. It also called Albright's hereditary osteodystrophy.
• Type Ib involves resistance to PTH only in the kidneys. Less is known about type Ib than type Ia. Many of the
  features are similar but the events that take place in the kidneys are different.
• Type II pseudohypoparathyroidism
  also involves low blood calcium and high blood phosphate levels. People with this form of the disorder do not have the physical traits common to people with Type Ia.

Symptoms

Symptoms are related to low levels of calcium and include:

• Cataracts
• Dental problems
• Numbness
• Seizures
• Tetany (a collection of symptoms including muscle twitches and hand and foot spasms)

Persons with Albright's hereditary osteodystrophy may have the following symptoms:

• Calcium deposits under the skin
• Dimples that can replace knuckles on affected fingers
• Round face and short neck
• Short hand bones, especially the bone below the 4th finger
• Short height

Exams and Tests

Blood tests will be done to check calcium, phosphorus, and PTH levels. You may also need urine tests.

Other tests may include:

• Genetic testing
• Head MRI or CT scan of the brain

Treatment

Your doctor will recommend calcium and vitamin D supplements to maintain proper calcium levels. If blood phosphate levels are high, you may need to follow a low-phosphorus diet or take medicines called phosphate binders (such as calcium carbonate or calcium acetate).

Outlook (Prognosis)

Low blood calcium in pseudohypoparathyroidism is usually milder than in other forms of hypoparathyroidism.

Possible Complications

People with type Ia pseudohypoparathyroidism are more likely to have other endocrine system problems (such as hypothyroidism and hypogonadism).

Low blood calcium in pseudohypoparathyroidism is often milder than in other forms of hypoparathyroidism.

Pseudohypoparathyroidism may be connected to other hormone problems, resulting in:

• Low sex drive
• Slow sexual development
• Low energy levels
• Weight gain

When to Contact a Medical Professional

Call your health care provider if you or your child has any symptoms of low calcium levels or pseudohypoparathyroidism.

Alternative Names

Albright's hereditary osteodystrophy; Types 1A and 1B pseudohypoparathyroidism

References

Wysolmerski JJ, Insogna KL. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Goldman L, Schafer AI. Goldman's Cecil Medicine, 24th ed. Philadelphia, Pa: Elsevier Saunders; 2012:chap 253.

Bringhurst FR, Demay MB, Kronenberg HM. Disorders of mineral metabolism. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2011:chap 28.

Doyle DA. Hypoparathyroidism. In: Kliegman RM, Stanton BM, St. Geme J, Schor N, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 565.

Update Date: 7/19/2012

Updated by: Shehzad Topiwala, MD, Chief Consultant Endocrinologist, Premier Medical Associates, The Villages, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.