Diagnosis and Treatment > Investigation > Liquid chromatography-mass spectrometry
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Search for other papers by Benjamin C Whitelaw in
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Summary
We describe severe hypokalaemia and hypertension due to a mineralocorticoid effect in a patient with myelodysplastic syndrome taking posaconazole as antifungal prophylaxis. Two distinct mechanisms due to posaconazole are identified: inhibition of 11β hydroxylase leading to the accumulation of the mineralocorticoid hormone 11-deoxycorticosterone (DOC) and secondly, inhibition of 11β hydroxysteroid dehydrogenase type 2 (11βHSD2), as demonstrated by an elevated serum cortisol-to-cortisone ratio. The effects were ameliorated by spironolactone. We also suggest that posaconazole may cause cortisol insufficiency. Patients taking posaconazole should therefore be monitored for hypokalaemia, hypertension and symptoms of hypocortisolaemia, at the onset of treatment and on a monthly basis. Treatment with mineralocorticoid antagonists (spironolactone or eplerenone), supplementation of glucocorticoids (e.g. hydrocortisone) or dose reduction or cessation of posaconazole should all be considered as management strategies.
Learning points:
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Combined hypertension and hypokalaemia are suggestive of mineralocorticoid excess; further investigation is appropriate.
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If serum aldosterone is suppressed, then further investigation to assess for an alternative mineralocorticoid is appropriate, potentially using urine steroid profiling and/or serum steroid panelling.
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Posaconazole can cause both hypokalaemia and hypertension, and we propose that this is due to two mechanisms – both 11β hydroxylase inhibition and 11β HSD2 inhibition.
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Posaconazole treatment may lead to cortisol insufficiency, which may require treatment; however, in this clinical case, the effect was mild.
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First-line treatment of this presentation would likely be use of a mineralocorticoid antagonist.
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Patients taking posaconazole should be monitored for hypertension and hypokalaemia on initiation and monthly thereafter.
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Anderson Cancer Institute, Memorial University Medical Center, Savannah, Georgia, 31404, USA
Search for other papers by Himangshu S Bose in
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Summary
Lipoid congenital adrenal hyperplasia (lipoid CAH), the most severe form of CAH, is most commonly caused by mutations in steroidogenic acute regulatory protein (STAR), which is required for the movement of cholesterol from the outer to the inner mitochondrial membranes to synthesize pregnenolone. This study was performed to evaluate whether the salt-losing crisis and the adrenal inactivity experienced by a Scandinavian infant is due to a de novo STAR mutation. The study was conducted at the University of North Dakota, the Mercer University School of Medicine and the Memorial University Medical Center to identify the cause of this disease. The patient was admitted to a pediatric endocrinologist at the Sanford Health Center for salt-losing crisis and possible adrenal failure. Lipoid CAH is an autosomal recessive disease, we identified two de novo heterozygous mutations (STAR c.444C>A (STAR p.N148K) and STAR c.557C>T (STAR p.R193X)) in the STAR gene, causing lipoid CAH. New onset lipoid CAH can occur through de novo mutations and is not restricted to any specific region of the world. This Scandinavian family was of Norwegian descent and had lipoid CAH due to a mutation in S TAR exons 4 and 5. Overexpression of the STAR p.N148K mutant in nonsteroidogenic COS-1 cells supplemented with an electron transport system showed activity similar to the background level, which was ∼10% of that observed with wild-type (WT) STAR. Protein-folding analysis showed that the finger printing of the STAR p.N148K mutant is also different from the WT protein. Inherited STAR mutations may be more prevalent in some geographical areas but not necessarily restricted to those regions.
Learning points
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STAR mutations cause lipoid CAH.
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This is a pure population from a caucasian family.
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Mutation ablated STAR activity.
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The mutation resulted in loosely folded conformation of STAR.
