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61

General FAQs / Treatment

« Last post by GinJones on January 21, 2015, 11:47:56 PM »

Treatment for XLH comes in two major categories:
Medication.
Surgical or orthopedic treatment.

Treatment almost always should take place at major research centers because of the rare nature of this disorder, and The XLH Network strongly suggests relying on specialists familiar with the condition and experienced in treating and managing it. These are most often endocrinologists or nephrologists with an interest in metabolic bone disorders.

Medications used in treating XLH – typically an active form of Vitamin D [such as Rocaltrol (Calcitriol) or ONE-ALPHA®] and phosphorus (such as K-PHOS®, Neutra-Phos®, or PHOSPHATE-SANDOZ®) – should be prescribed very carefully and taken in association with regular monitoring of blood and urine chemistries, including ParaThyroid Hormone (PTH) levels and urine calcium levels.  The focus should not be on how high the phosphorus level can increase, as might be appropriate for other causes of a low blood phosphorus level, because in XLH the more phosphate you take, the more you eliminate in the urine, and the higher the PTH may go...which you will want to avoid.  The medication can result in a variety of important effects on the kidneys that specialists will want to keep under tight control.
Progress is often measured in years, rather than months, so this can be very frustrating for parents and children alike. And if it’s not effective, or diagnosis came very late, surgical or orthopedic intervention may be required.

The XLH Network Inc. does not prescribe or suggest any particular treatment – that should be done by medical professionals and specialists in bone metabolism. These notes are provided based on the personal experience of members.

62

General FAQs / Diagnosis

« Last post by GinJones on January 21, 2015, 11:46:49 PM »

Without a family history of XLH, diagnosis (even when rickets symptoms are recognized) carries its own frustration.  Without experience in this unusual disorder, it is not unheard of for a physician to not even diagnose a child of an XLH parent until much later than it could be, putting bowing off to "bulky diapers" or saying "all toddlers legs are bowed" rather than even x-raying the child for rickets, or comparing the child's blood phosphorus level to an adult reference range since not all labs report the higher ranges seen in normally growing children.

XLH occurs probably in only one birth out of 20,000, so a pediatrician or general practitioner may never see it in his or her career.  Even if he does diagnose the child with rickets, he might not know about XLH and presume it to be due to lack of enough vitamin D and try that first.  However, XLH resists typical Vitamin D therapy, so a patient might then be put through a complete series of tests, X-rays, and consultations with specialists and then might not be diagnosed with XLH until age 3 or 4.

Precious treatment time is lost, so it's important to find a specialist with experience in this area when symptoms are first observed.  This type of specialist is generally an endocrinologist or nephrologist, but specifically one with an interest in metabolic bone disorders as opposed to more routine endocrine or nephrology issues.  Very few have experience in rare metabolic bone disorders, so it's important to make sure the one you see does.

If there's a family history of XLH, it should be easier to diagnose before symptoms of rickets even develop, but it's extremely important to compare lab results for serum phosphorus levels to normal levels for children of the same age, which some labs do not report.  In fact, the lab may not even indicate that the reference range is suitable only for adults, so a physician inexperienced with XLH may not realize the child's results are abnormal.  This causes an unnecessary delay in diagnosis.

Specialists who have several XLH patients, however, might diagnose a patient without much difficulty and know what tests to run to differentiate between the different disorders that cause rickets and osteomalacia.    The earlier the diagnosis, the earlier therapy can begin, and the better the results are likely to be.

There are several phosphate wasting disorders that cause similar symptoms to XLH, so it's  important to know which one the patient has since treatment for one might not be correct for another.   

People with Autosomal Dominant Hypophosphatemic Rickets can have symptoms that differ only in subtle ways from those experienced by people with XLH. ADHR, as indicated by its name, is another dominantly inherited hypophosphatemic disorder, but it is caused by a different gene found on a dfferent chromosome than XLH.   Its symptoms can first occur in people of any age, and in some cases its symptoms have even been found to resolve on their own.

And, certain very rare tumors [known by the names Tumor-Induced Osteomalacia (TIO) and Oncogenic Hypophosphatemic Osteomalacia (OHO)]  or rare cases of giant nevus sebaceous (certain very large birthmarks, which may be related to TIO) may also cause bone problems due to hypophosphatemia.  These disorders are not considered to be hereditary.

63

General FAQs / Overview of XLH symptoms in children

« Last post by GinJones on January 21, 2015, 11:36:05 PM »

X-Linked Hypophoshpatemia (XLH) is caused by one of several mutations of the PHEX gene, all of which cause XLH.  There does not seem to be any correlation between the specific mutation and the severity of the symptoms experienced.  Those with XLH generally exhibit the following:

Abnormal bone and tooth development, which may range from mild or moderate to severe.

Rickets that resists traditional Vitamin D therapy.

A few people with XLH exhibit no bone-related symptoms, and a study published in 1994 notes that it’s not uncommon for XLH to go undiagnosed in those with mild to moderate symptoms.

Lower limb deformities (bow or knock-knee)

Waddling gait

Short stature or declining growth rate

Spontaneous tooth abscesses

Bone pain

Muscle pain and weakness

SYMPTOMS SPECIFIC TO CHILDREN:

The child's wrists may be thicker than they should be, and when examined, the child's 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 the physician should be able to recognize this development called craniosynostosis very quickly when measuring the size of the child's head.

As the child grows older and starts walking, parents may not recognize an abnormality in the child’s gait, but relatives or acquaintances who are only in infrequent contact may express concern.

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 because of faulty formation inside the tooth – not decay or trauma – and some children may feel different degrees of pain in their legs.

64

General FAQs / Overview of XLH symptoms

« Last post by GinJones on January 21, 2015, 11:34:44 PM »

X-Linked Hypophosphatemia (XLH) is caused by one of several mutations of the PHEX gene, all of which cause XLH.  There does not seem to be any correlation between the specific mutation and the severity of the symptoms experienced.  Those with XLH generally exhibit the following:

Abnormal bone and tooth development, which may range from mild or moderate to severe.

Rickets that resists traditional Vitamin D therapy.

A few people with XLH exhibit no bone-related symptoms, and a study published in 1994 notes that it’s not uncommon for XLH to go undiagnosed in those with mild to moderate symptoms.

Lower limb deformities (bow or knock-knee)

Waddling gait

Short stature or declining growth rate

Spontaneous tooth abscesses

Bone pain

Muscle pain and weakness

65

Welcome / Under Construction

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