Neuromuscular disease and Osteoporosis link...

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SUBJ (8/01): THE OSTEOPOROSIS FACTOR

Is osteoporosis a complicating factor for those who're affected by spinal

muscular atrophy

(SMA type 3)? I mean, does the disease create a weakness in the bones that

predisposes

one to bone fracture? I'm 55 years of age.

REPLY from MDA: E. Mc, M.D., MDA Clinic Director, Neurology

Associates of

Arlington, Arlington, TX

Osteoporosis is a loss of calcium in our bones. This calcium is laid down in a

network of

tiny bony spicules. The spicules connect to one another in a 3 dimensional grid,

like the

steel girders that make up the supporting structure of a tall building or the

boards that

make up the frame of a house. As calcium is lost, these bony spicules become

thinner.

Ultimately, they can break in two. Once a bony spicule breaks, the two parts

never rejoin.

Over time, this loss of calcium causes the bone to become weaker, so that the

whole bone

can break. You can imagine that if many of the boards in the frame of the house

broke in

two, the remaining boards would not hold up the roof and the house would

collapse. As

bone density decreases from osteoporosis, the risk of fractures increases.

Men and women lose calcium progressively after age 30. Women have a rapid,

one-time

loss of bone calcium after menopause. Osteoporosis is a common, serious problem.

Hip

fracture and a curved, stooped spine are frequent results.

Weight bearing by bones tends to reduce or prevent osteoporosis. People who

cannot

stand and walk may have more rapid progression of osteoporosis because the bones

do

not bear the weight of the body every day. Neuromuscular diseases can accelerate

osteoporosis when people become unable to do much walking and standing. Weight-

bearing exercise, even standing holding on a chest of drawers for half an hour a

day, may

reduce this effect.

There is a type of x-ray called a DEXA that measures bone density and tells if

you have

osteopenia (reduced bone density) or osteoporosis (more severe reduction in bone

density). Generally, the test is done on the low spine and on the femur (thigh

bone).

Sometimes a wrist is also tested.

There are several things people can do to reduce or prevent osteoporosis. Women

can take

estrogen replacement therapy starting at the time of menopause. Men and women

can

take calcium in doses of about 1500 mg per day. You need about 200 to 400 units

of

vitamin D along with the calcium to absorb it well. Calcium citrate is a calcium

preparation

that may carry a lower risk of promoting kidney stones in persons who are prone

to

calcium kidney stones. If you are a stone former, a urologist can advise you

about this.

Calcium comes in many brands. Often the pills contain both calcium and vitamin

D. Brands

of calcium that you may see in the pharmacy include Caltrate, Citracal, Fosfree,

OsCal,

Tums, and many others.

Some drugs can be used in combination with calcium. Fosamax can be taken once

daily as

a 5 mg (for prevention) or 10 mg (for treatment) dose. Now there is a

once-a-week form

of Fosamax, with 70 mg pills taken one day per week. Actonel is a similar drug.

Both

drugs can sometimes cause bad irritation of the esophagus. Miacalcin is the form

of the

hormone calcitonin that comes in a nasal spray. People who are unable to take

Foxamax or

Actonel may be able to use Miacalcin. None of these drugs helps much unless you

take

calcium every day as well.

Your doctor can evaluate you for osteoporosis and prescribe appropriate

medication for

you.