By: The XLH Network Inc. Coordinators

Symptoms are what a person feels or experiences as abnormal. The biochemical disorder responsible for XLH cannot be felt or experienced, but the end result can. The primary symptoms of XLH are abnormal bone and tooth development, which may range from mild or moderate to severe.

• Symptoms in XLH are particularly variable. There are some people, perhaps five percent of those with XLH, who do not have any bone symptoms at all.
• Symptoms can compel and inform Diagnosis
• Symptoms that may be associated with XLH in Adults

Symptoms in XLH are particularly variable. There are some people, perhaps five percent of those with XLH, who do not have any bone symptoms at all.

The symptoms of XLH tend to appear when a child begins to bear weight on his or her legs. In a very young child (8-16 months), parents may notice bowing or twisting of the lower legs, or knock-knees. Their pediatrician may remark on the child's pronounced, or 'bossed,' forehead, while at the same time discounting the bowing as an effect of bulky diapers. The child's wrists may be thicker than they should be, and when examined, the child's little chest may have an array of bony beads (often called a rachitic rosary). Teeth may be slow to appear, and the child may be very small for his or her age. Rarely, there may be a problem with bone development in the head, and specialists should be able to recognize this very quickly. Doctors may use the term rickets, when they consider this collection of symptoms in children.

As the child grows older and starts walking, abnormality in his or her gait or legs may not be recognized by parents, but relatives or acquaintances who are only in infrequent contact may express concern. It's often at this point that parents realize that something must be done; suddenly the progressive bowing, twisting or knock-knees that have been a familiar characteristic of their child become dramatically apparent. The child's small stature may also be increasingly noticeable compared with his or her peers. Dental abscesses are a common complaint once teeth erupt, and some children may feel different degrees of pain in their legs.

Symptoms can compel and inform Diagnosis:

When there is no family history of XLH, rickets symptoms can often confound experts; there are many different causes for symptoms that are similar to those presented here. XLH occurs probably in only 1 birth out of 20,000, so it is not something a family doctor might ever be expected to see throughout the course of his or her career. Typically, after an exhaustive series of tests, X-rays, and consultations with an assortment of specialists, a young child may eventually be diagnosed with XLH, sometimes as late as 3 or 4 years old.

When there is a family history of XLH, parents usually know what symptoms to look for if they are concerned about XLH in their child. They will typically be more eager for their pediatrician to determine, by careful blood chemistry analysis within the first few months of life, whether their child has XLH. Conventional wisdom holds that the earlier the diagnosis, the earlier therapy can begin, and the better the prognosis. Diagnosis in these instances can usually be determined by careful blood chemistry analysis before any rickets symptoms are experienced.

[This information on symptoms of XLH in children has been compiled with particular reference to the exhaustive review on the biology and treatment of XLH rickets published in 1997 by Professor Thomas Carpenter.]

Symptoms that may be associated with XLH in Adults:

• People with XLH tend to be short and are usually in the lower percentiles for height. The XLH Network Inc. has produced a graphic snapshot of the height of its members, who range from profoundly short to within the normal range at around the 50th percentile.
• Tooth abscesses can continue to be a problem in adulthood, and The XLH Network Inc. members report a number of root canal procedures.
• Adults with XLH may experience different levels of bone pain. Sometimes this bone pain can be traced, by X-ray, to pseudo-fractures. These symptoms in adults may be referred to by the doctor as osteomalacia; literally, soft bones.
• Sometimes problems with joints (particularly knees) can occur which can be intermittent or chronic. These may be a result of calcification of ligaments, joints or tendons (enthesopathy), which occurs with increasing age. Joint problems may also be due to osteoarthritis that has developed due in large part to their misalignment as a result of childhood rickets or adult osteomalacia.
• Hearing problems may be a symptom that is associated with XLH; reports vary on frequency, though at least one expert estimates that nearly one third of his XLH patients have some hearing difficulties.
• Some adults with XLH (perhaps 10%, as determined in a straw poll of the mailing list for The XLH Network Inc. members) experience different levels of vertigo and nausea, a condition which is called Meniere's Disorder.
• Rarely, a condition called craniosynostosis or spinal stenosis can occur in XLH, in which growing bone presses on the brain or spinal cord causing nerve problems.

Many adult members of The XLH Network Inc. would think of themselves as relatively symptom-free, though they may have experienced rickets symptoms as a child.

This depiction of symptoms associated with XLH in adults should not be taken as a professional checklist of symptoms caused by XLH, but rather as a depiction of symptoms that members in The XLH Network Inc. have discussed in relation to their own condition.

Last modified Aug 8, 2007

XLH is also known as X-Linked Hypophosphatemia (sometimes also spelled as hypophosphataemia), X-Linked Hypophosphatemic Rickets, Familial Hypophosphatemia, Vitamin D-Resistant Rickets (VDRR) Rickets and even Genetic Rickets. Its notable characteristics are bowed legs, short stature, poor teeth formation causing spotaneous dental abscesses, and low blood phosphorus levels.

© 2002-2007, The XLH Network Inc.
The authors of this web site are not medical professionals, and this information does not substitute for medical care. Information on these pages is based on biomedical research, published in peer-reviewed journals, and international research conferences. Additionally, in some cases anecdotal information is provided by subscribers of the F-HYPDRR group, a mailing list for The XLH Network Inc. A complete web-site bibliography is available. Please read our full disclaimer.