E. 24 hr urinary collection of catecholamines – Explanation
Patients with neurofibromatosis may develop hypertension for three main reasons:
- coexistant essential hypertension
- phaechromocytoma
- renal vascular stenosis secondary to fibromuscular dysplasia
The normal renal function in this patient points away from a diagnosis of renal vascular disease
Phaechromocytoma therefore needs to be excluded first.
Neurofibromatosis
There are two types of neurofibromatosis, NF1 and NF2. Both are inherited in an autosomal
dominant fashion NF1 is also known as von Recklinghausen’s syndrome. It is caused by a gene
mutation on chromosome 17 which encodes neurofibromin and affects around 1 in 4,000
NF2 is caused by gene mutation on chromosome 22 and affects around 1 in 100,000
Features
| NF1 | NF2 |
| Café-au-lait spots (>= 6, 15 mm in diameter) Axillary/groin freckles Peripheral neurofibromas Iris: Lisch nodules in > 90% Scoliosis |
Bilateral acoustic neuromas |
