OSTEOPOROSIS AND PORPHYRIA
INTRODUCTION
The following principles should be borne in mind
when embarking on treatment for osteoporosis in patients with porphyria:
- Many of these patients
are the women over the age
of 50. In many cases, they
will have been diagnosed
as having porphyria 30 years
and more previously. Remember
that diagnostic testing
was often inaccurate in
the past; mistakes still
occur today. It is important
to review the diagnosis
of porphyria in every patient
requiring treatment for
osteoporosis. In most cases,
it is reasonable to repeat
the diagnostic testing modern
methods and confirm the
diagnosis.
- A sensible approach to
the management of osteoporosis
involves stepped-care as
follows: calcium supplementation,
hormonal replacement therapy,
bisphosphonates. It is wise
to introduce agents one
at a time according to this
schedule, rather than to
embark on across-the-board
therapy with several agents
at once. In this way, the
safety and duration of individual
agents can be assessed.
CALCIUM SUPPLEMENTATION
Dietary supplementation with milk, cheese
or mineral calcium in tablet form (as elemental calcium, calcium
carbonate or gluconate) is safe.
HORMONAL REPLACEMENT THERAPY
Female sex hormones
may be dangerous in patients with variegate
porphyria (VP) or acute intermittent porphyria
(AIP). They should never be lightly prescribed
as they may induce a life-threatening
acute attack of porphyria. There is clear
evidence that oestrogens and gestagens
have induced the acute attack in some
susceptible individuals with very serious
consequences. The risk is greater in patients
with AIP than in those with VP, and gestagens
appear to be more dangerous than oestrogens.
Many patients with VP will however tolerate
oestrogens and even combined preparations,
but unfortunately such a happy outcome
cannot be guaranteed. It is essential
to follow the guidelines below when prescribing
them.
For further information:
Hormonal
therapy and family planning in porphyria
BISPHOSPHONATES
All members of
this class are regarded as safe, as they
are essentially not metabolised within
the body.
OTHER THERAPY
Both vitamin D and calcitonin are likely
to be safe.
PRECAUTIONS TO FOLLOW WHEN
INTRODUCING DRUGS OF UNPROVEN
SAFETY
This includes the
use of oestrogen and gestagens in particular.
- Introduce agents one
at a time.
- Warn the patient that
the agent is not guaranteed
safe; obtain their consent
for its use; warn them to
cease medication and report
back to you immediately
in the event that they develop
abdominal pain.
- Where hormonal supplementation
is prescribed, use an oestrogen-only
preparation such as Premarin,
particularly if the patient
has had a hysterectomy.
If you regard it as important
to use a combined oestrogen-gestagen
preparation, extra caution
is necessary. Use the lowest
possible dose and follow
the patient closely.
- Avoid the use of hormonal
therapy, particularly gestagens,
in patients with AIP and
in those with a history
of more severe porphyria,
especially those who have
suffered acute attacks within
the past few years.
Return
to top of page
|
