Thanks to Robert Beetham for suggesting this pre-analytical enquiry.
You are asked for advice by a Community Physician. His patient is a 52 year
old lady with a Cushingoid pattern of obesity and hirsutism. Her current
medication is 25 mg prednisolone for polymyalgia rheumatica, and a range of
drugs for schizophrenia. How should she be investigated for Cushing's
syndrome?
This difficult problem attracted 27 participants.
3 said 'impossible'; 1 said 'these Cases get more difficult every
week' (thank you Chris, but it's not intentional);
1 said 'search me, guv' (thank you, William); and 1 (bless you, David) said
'interesting case. It's nice to see a pre-analytical question'.
2 participants thought biochemistry was unlikely to be helpful, and
suggested MRI scan of the pituitary fossa, and ultrasound scan of the
adrenals;[1.3]
1 participant would measure a serum cortisol;[-1.3]
5 pointed out that prednisolone cross-reacts with most cortisol
assays;[1.3]
1 participant would measure cortisol by an HPLC assay in which prednisolone
does not cross-react;[1.0]
6 would measure ACTH (which should be suppressed);[0.4]
5 would measure urine cortisol if the method did not suffer cross-reaction
from prednisolone;[0.5]
6 suggested stopping prednisolone before investigation;[-1.5 - see
footnote]
3 of these suggesting a dexamethasone suppression test after prednisolone
withdrawal;
4 suggested changing to dexamethasone before investigation. [1.3]
2 asked how long the patient had been on prednisolone; [-0.3]
2 queried other clinical evidence of hypercortisolism.[0.3]
9 participants said that this high dose of prednisolone could be
responsible for the clinical picture; [1.3]
2 suggested a review of her drug therapy;[-0.3]
5 suggested reducing prednisolone if possible. [0.3]
6 stated that prednisolone should not cause hirsutism; [0.3]
4 of these would measure testosterone; [0.6]
2 would ask for a urine steroid profile; [0.5]
1 stated that hirsutism is a recognised complication of prednisolone
therapy; [0.7]
1 queried whether the hirsutism was age-related; [0.0]
1 suggested androgen measurements if there was any possibility of an
adrenal tumour. [0.7]
Only 1 participant suggested referring the patient to an endocrinologist!
[1.7]
The patient had been on prednisolone for 6 months and the dose was now
slowly being reduced. Bob Beetham told the Family Doctor that this was a
complex problem, and screening tests for Cushing's in this situation were
likely to be misleading for several different reasons. The Family Doctor
appeared not to have undertaken a full physical examination, measured blood
pressure or noted skin appearance. Bob suugested referral of the patient to
an endocrinologist.
Footnote. One assessor points out that simply stopping prednisolone in this
situation carries a significant risk of blindness, since giant cell
arteritis can accompany polymyalgia rheumatica.
With this summary, Cases for Comment are one year old - the first Case was
distributed on 13 October 1997! Just for once, the 13th was an auspicious
day.
I am going on leave for two weeks - Case 43, and the summary of Case 42
will appear in the first week of November.
Best wishes
Gordon Challand
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