Persistent Hypertension Despite Successful Dilation of a Stenotic Renal Artery in a Boy With Neurofibromatosis Type 1

Improved renal function in neurofibromatosis type 1 patients

Neurofibromatosis type 1 (NF1), or von Recklinghausen disease, is an autosomal dominant disease that presents with various symptoms, including café‐au‐lait spots and neurofibromas. NF1 patients occasionally suffer from renal artery vasculopathy, which impairs renal function, while results of a previous report suggested that male NF1 patients have a low creatinine level in peripheral blood. The assessment of renal function in NF1 patients remains inadequate. In this study, renal function in NF1 was assessed. We recruited 308 patients consisting of 149 NF1 patients (77 males and 72 females) and 159 control patients (102 males and 57 females). Creatinine, blood urea nitrogen and haemoglobin A1c in peripheral blood as well as protein, occult blood and sugar in urine were examined. In addition, the estimated glomerular filtration rate was calculated. The mean age and body mass index did not differ significantly between the NF1 patients and controls for both sexes. For both sexes, i) the mean creatinine value was significantly lower in the NF1 patients than in the controls; ii) the mean blood urea nitrogen value did not differ significantly between the NF1 patients and controls; iii) the mean blood urea nitrogen‐to‐creatinine ratio was significantly higher in the NF1 patients than in the controls; iv) the mean estimated glomerular filtration rate was significantly higher in the NF1 patients than in the controls; and v) the mean haemoglobin A1c value was significantly lower in the NF1 patients than in the controls. In conclusion, NF1 patients may have improved renal function. The clinical significances should be further examined.

Hypertension in Children and Adolescents with Turner Syndrome (TS), Neurofibromatosis 1 (NF1), and Williams Syndrome (WS)

PURPOSE OF REVIEW

Turner syndrome (TS), neurofibromatosis type 1(NF1), and William Syndrome (WS) are 3 genetic conditions that are all associated with a substantial increase in risk of hypertension. In this review, we focus on factors leading to hypertension and on clinical manifestations and management of hypertension in children and adolescents with these genetic conditions RECENT FINDINGS: In most instances, hypertension is secondary. There is a high prevalence of masked hypertension in TS; however, the extent to which control of the BP helps reduce the risk of aortic dissection/aneurysm in TS is not yet fully elucidated. Vasculopathies are the least emphasized but most important manifestation of NF1. Of note, routine screening for pheochromocytoma in NFI is not recommended as it is not cost-effective. Cardiovascular complications are the major cause of death in patients with WBS. ABPM identifies patients without overt aortic or renovascular narrowing. Antihypertensive agents such as ARBs that have direct vascular wall effects and agents that inhibit oxidative stress (minoxidil) should be considered, even in those who do not exhibit overt hypertension. Elevated blood pressure in children and adolescence manifests early with end-organ changes and when left untreated, increases risk for premature onset of cardiovascular disease. Vigilant monitoring of the blood pressure is recommended. Accurate early diagnosis and management of hypertension will delay or prevent target organ damage and ensure a healthier transition to adulthood among children afflicted with these conditions.

Ask-Upmark kidney in a girl with neurofibromatosis type 1

Ask-Upmark kidney (AUK) is a scarred segment of the kidney, characterized by formation of primitive tubular and glomerular structures, and sporadically diagnosed as a cause of hypertension (HTN). A 6-year-old girl with neurofibromatosis type 1 (NF1) and moyamoya syndrome had severe HTN. Based on past history, she had HTN at the age of 1.5 years. Laboratory examination revealed slightly elevated plasma and renal venous renin activity without lateralization. No evidence of pheochromocytoma, or coarctation of the aorta was found. Contrast-enhanced computed tomography (CT) showed an area of hypoperfusion in the upper and middle poles with reduced size of the right kidney. The results of dimercaptosuccinic acid scintigraphy were in accordance with those of contrast-enhanced CT. Selected renal arteriography revealed a paucity of peripheral vascularity in the same parts of the right kidney. In the absence of a history of urinary tract infection and vesicoureteral reflux by cystography, we presumed that the severe HTN may be due to segmental hypoplasia of the kidney, AUK, with a possible contribution from NF1. Although renal artery stenosis and pheochromocytoma are well-known causes of HTN in NF1, this case demonstrates that HTN can be caused by AUK in patients with NF1.

Pheochromocytoma Diagnosis After an Abnormal Stress Test: Case Report and Review of the Literature

Pheochromocytoma is a rare adrenal gland tumor that is often difficult for physicians to diagnose because of its general, nonspecific complaints. Diagnosis is particularly difficult in patients with neurofibromatosis 1, because pheochromocytoma in these patients will mimic other cardiovascular abnormalities. The authors report the case of a 60-year-old woman with an extensive history of hyperlipidemia, malignant hypertension, coronary artery disease, and neurofibromatosis 1 who was referred for an elective cardiac catheterization as a result of an abnormal stress test. The patient returned to the hospital 3 days after the procedure complaining of increased angina and palpitations. While hospitalized, she developed severe episodic hypertension. A computed tomographic scan revealed bilateral adrenal masses. Findings of biochemical and imaging evaluation confirmed the diagnosis of bilateral pheochromocytoma. Early screening of pheochromocytomas in high-risk populations is essential for prompt diagnosis and successful management.

White-Coat and Reverse White-Coat Effects Correlate with 24-h Pulse Pressure and Systolic Blood Pressure Variability in Children and Young Adults

Masked hypertension (MH) and white-coat hypertension (WCH) are associated with organ damage. In the present study, we examined the correlation between the magnitude of white-coat effect (WCE) or reverse WCE (RWCE) and 24-h pulse pressure (PP), an indicator of target organ damage and arterial stiffness, in children and young adults. We also examined the relationship of WCE or RWCE and blood pressure (BP) variability, another predictor of clinical outcomes. One hundred and ninety-eight subjects were studied. According to the office BP and ambulatory BP, they were divided into normotension, WCH, MH, and hypertension. The magnitude of WCE or RWCE, along with male gender and 24-h systolic BP, was the determinant of 24-h PP. In subjects with 24-h PP ≥ 61 mmHg, the magnitude of WCE or RWCE, age, male ratio, height, weight, BMI, the percentage of secondary hypertension, that of MH, office systolic BP, and 24-h systolic BP were significantly greater. There was a progressive increase in 24-h PP from normotension, WCH, MH, to hypertension. BP variability in subjects with MH was numerically highest in both systolic and diastolic. Diastolic BP variability of WCH, MH, and hypertension was significantly higher than that of normotension. Finally, the magnitude of WCE or RWCE in systolic showed a significant correlation with systolic BP variability. In conclusion, the magnitude of WCE or RWCE correlates with 24-h PP and systolic BP variability, which may suggest increased arterial stiffness in WCH and MH.

Double NF1 inactivation affects adrenocortical function in NF1Prx1 mice and a human patient

BACKGROUND

Neurofibromatosis type I (NF1, MIM#162200) is a relatively frequent genetic condition, which predisposes to tumor formation. Apart from tumors, individuals with NF1 often exhibit endocrine abnormalities such as precocious puberty (2,5-5% of NF1 patients) and some cases of hypertension (16% of NF1 patients). Several cases of adrenal cortex adenomas have been described in NF1 individuals supporting the notion that neurofibromin might play a role in adrenal cortex homeostasis. However, no experimental data were available to prove this hypothesis.

MATERIALS AND METHODS

We analysed Nf1Prx1 mice and one case of adrenal cortical hyperplasia in a NF1patient.

RESULTS

In Nf1Prx1 mice Nf1 is inactivated in the developing limbs, head mesenchyme as well as in the adrenal gland cortex, but not the adrenal medulla or brain. We show that adrenal gland size is increased in NF1Prx1 mice. Nf1Prx1 female mice showed corticosterone and aldosterone overproduction. Molecular analysis of Nf1 deficient adrenals revealed deregulation of multiple proteins, including steroidogenic acute regulatory protein (StAR), a vital mitochondrial factor promoting transfer of cholesterol into steroid making mitochondria. This was associated with a marked upregulation of MAPK pathway and a female specific increase of cAMP concentration in murine adrenal lysates. Complementarily, we characterized a patient with neurofibromatosis type I with macronodular adrenal hyperplasia with ACTH-independent cortisol overproduction. Comparison of normal control tissue- and adrenal hyperplasia- derived genomic DNA revealed loss of heterozygosity (LOH) of the wild type NF1 allele, showing that biallelic NF1 gene inactivation occurred in the hyperplastic adrenal gland.

CONCLUSIONS

Our data suggest that biallelic loss of Nf1 induces autonomous adrenal hyper-activity. We conclude that Nf1 is involved in the regulation of adrenal cortex function in mice and humans.

Renal artery stenosis due to neurofibromatosis type 1: case report and literature review

Background

Neurofibromatosis type 1 (NF1) is a relatively common autosomal dominant disorder. The most common vascular abnormality in patients with NF1 is bilateral or unilateral renal artery stenosis.

Case report

A 16-year-old boy presented with a headache of 4-year duration and was found to be moderately hypertensive. On physical examination, axillary freckling and multiple café-au-lait spots were revealed over the trunk, while numerous small nodules were palpable on the limbs. Biopsy of subcutaneous nodule showed neurofibroma. Lisch nodules were identified on slit-lamp examination and grade I hypertensive retinopathy was present on fundoscopy. Clinical laboratory investigations revealed that renal and liver function tests, blood cells count, urinalysis, serum electrolytes, serum levels of renin and aldosterone, and 24-hour urine levels of catecholamines were all within normal ranges. Abdominal ultrasound and CT were normal. Both kidneys were of normal size. CT angiography showed right renal artery stenosis (>90%) at the ostium. The final diagnosis of NF1 with right renal artery stenosis and secondary hypertension was then made. The patient was treated with Procardin (30 mg/d) and improved with a significant decline in blood pressure. The main outcomes were to control blood pressure without necessarily proceeding with PTRA. We also present a review of the literature.

Conclusions

NF1 may present with hypertension due to renal artery stenosis in children. All young patients (<30 year) with hypertension should be clinically screened for secondary causes of hypertension, including NF1, so that renal revascularization can be offered before permanent end organ damage has occurred. First-line management using medication alone could be appropriate, keeping the interventional options for when the patient's condition deteriorates.