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Osteoporosis & Pagets
Disease The human skeleton is
made up of 212 bones 206 sizable and six little bones known as ossicles,
three in each ear. Bones work with ligaments, tendons, and joints to provide
movement of the skeleton. Bones provide an outer shell to protect our internal
organs. Bones house bone marrow, the main source of blood formation. Bones
serve as a source of calcium for the entire body. Bone formation begins in the
fetus approximately 12 weeks after conception and is not gen-erally complete
until adolescence although maximum density is not reached until age 30.
Actually, bone formation is never complete. It is constantly being destroyed or
broken down and formed anew or rebuilt throughout our lifetime. The process is
normally in precise balance. There are three distinct cell types responsible
for the maintenance and making of bone.
- Osteocytes or bone cells
that maintain bone as living tissue
- Osteoclasts or bone breakers
that destroy bone
- Osteoblasts or bone builders
that form the supporting matrix of new bone
Osteoporosis or holes in
the bones causes the bones to become brittle and is the leading bone
disease in the United States. The progressive decrease in bone density occurs
in both men and women, but is most common among postmenopausal women when bone
resorption (destruction) exceeds that of bone formation. To maintain bone
density, the body requires an adequate supply of calcium and other minerals and
must produce the proper mix of several hormones as well as an adequate supply
of vitamin D to absorb calcium from food. When the body is not able to regulate
the mineral content of bones, they become less dense, more fragile and more
prone to fracture. From age 50 to 90, the risk of hip fracture in white women
(Caucasian and Asian women have a higher risk factor for osteoporosis)
increases 50-fold and the risk of vertebral fracture increases 15- to 30-fold.
It is estimated that 40 percent of 50-year-old women will sustain one or more
osteoporo-sis- related fractures of the spine, hip, or wrist during their
remaining lifetimes. Hip fractures in particular, are associated with
substantial morbidity, disability, and mortality in both men and women over 70.
There are 1.3 million osteo-related fractures in the U.S. each year.
Osteoporosis has long been considered a womans disease an
estimated 23 million women have osteoporosis so not many studies have
been done with men. Studies focused on men are not far off. Presently it is
estimated that 2 million men have osteoporosis with another 3 million at
risk.
Pagets Disease, named for
Sir James Paget, an English doctor who first described the diseases
characteristics in 1876, is the second most common bone disease in the United
States. Often pain-ful, Pagets Disease is a disruption in the normal
activity of bone tissue. Overly large osteoclasts dissolve bone too quickly
up to 50 times faster than normal. Osteoblasts try to compensate for the
increased pace by hurriedly depositing new bone, but the rate is so rapid that
the new bone is loose and bulky in structure, rather than strong, compact, and
neatly arranged. Over time, the affected bone becomes weak and soft and can
easily bend and may shorten the leg or spine. The disease can also enlarge the
diameter of the bone. No bone is sacrosanct, but the most common bones affected
are those of the spine, skull, pelvis, and legs. Deformities include bowed
legs, an enlarged head or pelvis, and a curved back. If it changes bones around
joints, it can cause arthritis or dental prob-lems when it affects facial
bones. People with Pagets and heart disease may be at greater risk for
heart failure because Pagetic bones often contain more blood vessels than
normal so the heart has to work harder to pump the extra blood required. It is
estimated that three percent of the population over 40 is affected, but because
it often develops without symptoms, 58 is the average age of
diagnosis.
There is no known cause for
Pagets Disease, but genetics are strongly suspected because the disease
tends to run in families. According to the Paget Foundation, the disease is
most common in Cauca-sian people of Anglo-Saxon and European descent, but it
also occurs in African Americans. It is rare in people of Asian descent. The
precise gene has yet to be identified, but Frederick Singer, M.D., an
endocrinologist at St. Johns Hospital (Santa Monica, CA), has traced an
abnormality to chromo-some 18. Singer and other experts also suspect that a
slow virus (one which does not cause symp-toms for many years) may play a role
because osteoclasts from patients with Pagets Disease contain the measles
virus messenger RNA whereas osteoclasts of people without the disease do not
contain this RNA.
Many people discover they have
Pagets purely by accident from an x-ray taken for another reason
or when a routine blood test shows an abnormally high level of total alkaline
phosphatase, an en-zyme produced by osteoblasts as well as cells of the
intestine and liver. When osteoblasts are overly active, the enzyme spills over
into the blood. A normal serum alkaline phosphatase ranges from 20 to 141 units
per liter. People with severe Pagets Disease may have six to 10 times
that range. One of the drugs prescribed to treat both osteoporosis and
Pagets Disease, is Fosamax (alendro-nate) which was approved by the
FDA in 1995. Fosamax was approved for women only although the manufacturer,
Merck, is sponsoring studies on men and has applied for FDA approval. Fosamax
is an aminobisphosphonate that acts as a specific inhibitor of bone destruction
by osteoclasts. Sim-plistically, the drug tips the balance in favor of bone
building osteoblasts so new bone is being made faster than old bone is being
destroyed. A constant supply of the drug is necessary to maintain the upper
hand. The recommended dosage for osteoporosis is 10 mg. per day and a
months supply costs $50.00. Dosage for Pagets Disease can be as
high as 40 mg. per day at a cost of $126.00 per month.
Fosamax is difficult to absorb.
Patients are instructed to take the drug on an empty stomach with a minimum of
8 ounces of water at least 30 minutes before breakfast. Most important,
patients should not to lie down until after their first food of the day. The
drug warnings include esophagitis, esophageal ulcers and esophageal erosions
along with irritation of the upper gastrointestinal tract. In fact, Fosamax is
number one on the FDAs list of drugs suspected for causing adverse
reactions. (The reports which are voluntary, totalled 174,905 in the past year.
Fosamax accounted for 3.5% or 6,197 of the reports.) Additionally, patients
should be instructed not to chew or suck on the tablet or take the drug at
bedtime.
No human trials were done with
pregnant or nursing women, but those done with rats indicate that extreme
caution be exercised by the physician and patient when considering Fosamax. The
doses used for the rat studies were higher than those recommended for humans,
but protracted labor, maternal late pregnancy death, and fetal death were
observed.
Other side effects reported by
the investigators included abdominal pain, nausea, indigestion, constipation,
diarrhea, gas, acid regurgitation, vomiting, difficulty swallowing, abdominal
bloating, gastritis, musculoskeletal pain, and headache. Avoid the drug if
possible. |