Our son born in 1987, is under treatment for Hypophosphatemic Vitamin D-Resistant Rickets (HVDRR) now more commonly known as X-Linked Hypophosphatemia (XLH), diagnosed when he was two and a half years old.
This is a metabolic gene disorder first identified in the 1930's, and although comparatively rare, is now recognized as the most common form of rickets in the developed world. It is not nutrition related. The genetic defect, which is passed down via the X-Chromosome, is known to cause renal tubular phosphate wasting, and is theorized to also affect Vitamin D metabolism. It affects the bones, teeth, kidneys, parathyroid gland, and upsets the balance of calcium/phosphate levels. Naturally growth is stunted. Untreated it appears to lower the immune system, (not noted scientifically) which allows the infant sufferer to catch every cold, flu and ear infection that comes around.
At present, the best treatment requires daily doses consisting of 1-alpha-hydroxycholicalciferol (a Vitamin D3 supplement) and Neutra-phos (a sodium phosphate). Treatment has evolved over the years from straight Vitamin D or phosphate supplementation only, to combinations of both, using different variations of Vitamin D to compare re-absorption levels for calcium and phosphate. Since there have been few studies possible under consistent treatment regimens, and given the widely varying degrees of severity from one patient to the next, there is little known of long-term effects of the treatment itself. Currently, there is growing evidence to indicate that nephrocalcinosis (a deposition of calcium phosphate in renal tubules) of the kidneys is a probable outcome of the treatment. Nephrocalcinosis blocks the tubules and decreases the ability to function properly-causes kidney stones and possible renal failure.
My son showed early bowing of legs, tibial torsion, frontal bossing, and enlarged wrist and ankle joints. His head appears abnormally large, as well. His height growth pattern before treatment was not even near the chart standard percentiles. Since treatment, he has remained below the 5th percentile or between the 5th and 10th.
We suspected something was wrong due to the above symptoms, but accepted the opinion of our G.P, pediatric and orthopedic specialists; all of whom had varying diagnoses from: "his diapers are to large", to: "he needs a brace to straighten his legs out", to: "it's just him - his father's family is short with big heads, too"!
Luckily, (sort of) he contracted pneumonia, and was seen again by the same pediatric specialist. It was then he noticed his skeletal abnormalities such as barreled chest, bowed legs, toed-in feet, short stature and large head. He had trouble even toddling. The doctor then referred him to BC Children's Hospital for metabolic and genetic testing.
There he was diagnosed with HVDRR (XLH); a spontaneous, or sporadic case, having no family history.
In 1995 at age nine, he was having many challenges with his dental health. Most, or at least, many dentists have little knowledge of this disease, and its effect on teeth. Paradoxically, dentists could sometimes be the first health professionals to diagnose a patient, especially in those patients (usually females) who do not present bone malformation as severely. His teeth, upon visual examination, look beautiful, hard and well-formed. There is no enamel hypoplasia, as some might expect. It is in the formation of the unseen dentin and pulp that there are problems. This even fooled a pediatric dental specialist, who saw him when he was five years old, and who could have prevented most of his future tooth loss.
He has had, to date, all of his upper, and four lower primaries removed due to abscessing. His remaining primaries were sealed with chrome crowns for the less noticeable teeth, and a coating for the visible canines. Periapical x-rays taken during the crowning procedure showed a shadow in the erupting upper front left secondary tooth, possibly indicating it was already compromised.
Medically speaking, his rickets appear, under radiology, to have healed. We are concerned about the possibility of tertiary hyperparathyroidism (usually requiring a parathyroidectomy), nephrocalcinosis brought on by the drug therapy (which could result in renal failure) and of course, osteomalacia in his adulthood.
By way of update, in 2000, five years after his dental operations, he has suffered no more abscesses, and is almost completed successful orthodontic work to have his teeth straightened as they came in. The primaries that were capped and since fallen out also gave him no more trouble. A definite personal indication that at present that treatment (chrome crowns on primaries) is the best chance for a nice smile and healthy teeth.
Any parents reading this will already be concerned that doctors and other health professionals, with their busy schedule, volumes of information they must try and remember, and their own personal challenges, cannot be expected to know everything, or to always make the right decisions. As parents, if we suspect a problem, we must follow it up thoroughly and to our satisfaction. Once diagnosed, if the problem is rare, or new to your doctors, nurses, and dentists, we must educate ourselves enough so that we may increase their knowledge to better deal with our child who happens to be their patient.
If your doctor or dentist is unwilling to believe you, or admit they don't know the answer, or even listen to your questions, move on to someone else who will.
Our purpose in writing this article is to raise awareness of this disorder which, although rare, will by nature of its genetic transmittal become more prevalent. Undeveloped countries usually present nutritional rickets problems; genetic cases are prevalent in developed nations. We therefore suspect there may be links between either the mother's work environment, or heavy metal toxicity, or pesticides and pollution, and the spontaneous generation of HVDRR. If so, this disorder will no doubt multiply. In any case, our focus should not be on the ultimate causes of a spontaneous case, but to find a cure, and support those with XLH until one is found.
One of our main goals is to create a support group or a society of some sort, to initiate and continue research into the disorder.
In the research area, we are interested specifically in the pursuit of the following:
If anyone reading this article happens to be, or knows of, a researcher, doctor, dentist, or biochemist, interested in this field, or a sufferer of this disorder, please provide us with their contact information, if they are agreeable.
Contact us through via email:
Colin Steeksma
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