Let's talk about the metabolic bone diseases.
We'll cover osteoporosis, vitamin D deficiency,
osteomalacia and end with Paget's disease of the bone.
In this case, a 64-year old female presents in the
clinic with a history of 3 fractures in the past year
with the last one being a month ago.
Her bone density screening from last
year reported a t-score of -3.1
and she was diagnosed with osteoporosis.
She was advised to quit smoking and alcohol and
was given calcium and vitamin D supplementation.
What is the next best step in
the management of this patient?
This patient has severe osteoporosis with
multiple fractures and very low bone density.
In fact a bone density of under -1.5
implies the presence of osteoporosis.
The conclusion here is we have
inadequately treated severe osteoporosis
and we should prescribe a
bisphosphonate for this patient
Osteoporosis not responding to lifestyle modifications
is usually an indication to commence pharmacotherapy.
Start with the bisphosphonates,
for example alendronate.
on DEXA scan, this patient has a t-score of -3.1 and
for the past year, she has had 3 bone fractures.
A t-score of greater than -1.5 is considered normal
while between -1.5 and -2.5 is defined as osteopenia
A score of less than -2.5 is diagnostic for osteoporosis
which is due to the decrease in the mineral density of bones
leading to fragile bones prone to
fracture even with minor trauma.
Risk factors for osteoporosis are numerous.
They include old age, female gender, postmenopausal
states, family history of osteoporosis,
ethnicity, low body mass index, low levels of vitamin
D and calcium, diet lacking in vegetables and fruits,
a sedentary lifestyle in which there is no exercise, smokers, patients
who drink alcohol, patients who have a high intake of caffeine
and patients who are on drugs like
corticosteroids and proton pump inhibitors.
Risk factors for low bone density in osteoporiosis
can be divided into lifestyle or modifiable,
non-modifiable and then those related
to medications and supplement use
Looking at the modifiable factors, alcohol use, immobilzation,
low body mass index, low calcium intake, smoking,
vitamin D deficiency, wight loss and recurent falls are all things
that can be modified to try to improve the patient's osteoporosis
and limit the damage to their bones.
Non-modifiable factors include
race and ethnicity, age and gender.
The classic presentation with osteoporosis is a
Caucasian female who is post menopause, who smokes.
Firs degree relatives with low bone mineral
density should have genetic evaluations,
they may present with hypophosphatasia and
other syndromes like Ehlers-Danlos Syndrome
and osteogenesis imperfecta
should be ruled out.
Finally, medications and supplements that may
be associated with osteoporosis are numerous.
The anticonvulsants, antiretrovirals like Tenofovir
in patients with HIV, aromatase inhibitors,
calcineurin inhibitors in patients who are
requiring imune suppression post transplant,
and then glucocorticoids.
This is a dose-dependent relationship so
anything more than 5 mg per day of Prednisone
or the equivalent for more than three months will increase
the patient's risk of developing osteoporosis
Further review of medications include heparin, gonadotrophin-releasing
hormone agonist which are used in infertility treatment,
proton pump inhibitors, thiazolidinediones
which are used to treat diabetes
Lithium and finally androgen deprivation therapy that
one may use to treat patients with prostate cancer
Alendronate is prescribed for this patient because she has not
really responded to non-pharmacologic therapy up to this point.
Bisphosphonates inhibit the
resorption of bone by osteoclasts
and may have an effect on osteoblasts which
are responsible for bone mineralization.
After taking alendronate, always remember to remind patients to
remain upright for at least 30 minutes to avoid esophagitis.