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Table of Contents
BRIEF REPORT
Year : 2018  |  Volume : 1  |  Issue : 2  |  Page : 90-92

Hypertension with metabolic alkalosis


1 Department of Pediatrics, Division of Nephrology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Cardiac Radiology, All India Institute of Medical Sciences, New Delhi, India

Date of Web Publication27-Dec-2018

Correspondence Address:
Dr Aditi Sinha
Department of Pediatrics, Division of Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/AJPN.AJPN_20_18

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  Abstract 


Severe hypertension in children is chiefly renal parenchymal or renovascular in origin. Renovascular hypertension is usually symptomatic and rarely presents with renal tubular dysfunction. We describe a 2-year-old child with polyuria, failure to thrive, hyponatremia, hypokalemia, metabolic alkalosis, hypercalciuria, low molecular weight proteinuria, and medullary nephrocalcinosis. Evaluation revealed severe hypertension and discrepant renal sizes. Doppler ultrasonography and digital subtraction angiography showed right main renal artery stenosis. Hypertension and electrolyte abnormalities abated following percutaneous angioplasty. Unilateral renal artery stenosis may manifest with symptoms of renal tubular dysfunction alone. Hypokalemia and metabolic alkalosis must prompt consideration of renovascular hypertension and monogenic causes. Angiography is essential for confirmation of renovascular hypertension and enables angioplasty, the mainstay of management.

Keywords: Fibromuscular dysplasia, hyponatremic-hypertensive syndrome, renovascular hypertension


How to cite this article:
Sharma A, Khandelwal P, Sinha A, Kumar S, Hari P, Bagga A. Hypertension with metabolic alkalosis. Asian J Pediatr Nephrol 2018;1:90-2

How to cite this URL:
Sharma A, Khandelwal P, Sinha A, Kumar S, Hari P, Bagga A. Hypertension with metabolic alkalosis. Asian J Pediatr Nephrol [serial online] 2018 [cited 2019 Jan 22];1:90-2. Available from: http://www.ajpn-online.org/text.asp?2018/1/2/90/248635




  Introduction Top


Renal tubular dysfunction should be suspected in children with failure to thrive, polyuria, refractory rickets, hypokalemia, and metabolic acidosis or alkalosis.[1] While polyuria can result from excessive fluid intake or defects in release or action of antidiuretic hormone, it is most often due to solute diuresis in primary renal tubular disorders. Polyuria, hypokalemia, and metabolic alkalosis may be the manifestation of conditions causing ineffective renal tubular electrolyte reabsorption (Bartter and Gitelman syndromes) or increased mineralocorticoid action (renovascular hypertension, renin-secreting tumor, primary hyperaldosteronism, and monogenic forms of hypertension).[1],[2] These conditions must be differentiated from systemic causes including vomiting, hypomagnesemia, cystic fibrosis, and diuretic use. We report a child with a rare but treatable condition, presenting with polyuria since infancy and masquerading as a primary renal tubular disorder.


  Case Report Top


A 2-year-old boy presented with complaints of polyuria, polydipsia, failure to thrive, and salt craving since 10 months of age. The child would wake up to drink and void several times at night; weight gain was inadequate, despite attention to diet. Following an episode of vomiting 1-month back, the child had weakness with inability to sit up that recovered following intravenous (IV) hydration. There was no history of seizures, tetany, or visual or hearing deficits; antenatal and postnatal course was unremarkable; development was appropriate for age; and family history was noncontributory.

The patient was dehydrated with sunken eyes and dry oral mucosa. The weight was 9.3 kg (−2.5 standard deviation score [SDS]) and length was 81 cm (−2.0 SDS). Pulse rate was 100/min, regular and palpable in all limbs; there was no radio-femoral delay. Blood pressure was between 180/100 and 156/90 mm Hg (>95th centile for age, sex, and height centile + 12 mm) in right upper limb, with no difference in the four limbs. Systemic examination was noncontributory except for hypertensive retinopathy; there were no abdominal or subclavian bruits, bony deformities, or neurocutaneous markers. Electrocardiogram showed left ventricular hypertrophy. The patient received therapy with oral amlodipine, prazosin, and labetalol.

The arterial blood pH was 7.45–7.50, bicarbonate 44–47 mEq/L, potassium 2.6–3.2 mEq/L, sodium 118–127 mEq/l, chloride 84–86 mEq/l, and hemoglobin 16–17 g/dl. Blood levels of creatinine (0.2–0.3 mg/dl), glucose (90 mg/dl), calcium (8.9 mg/dl), phosphorus (4.3 mg/dl), and magnesium (2.3 mg/dl) were normal. Serum and urine osmolality were 284 mOsm/kg and 237 mOsm/kg, respectively. Urinalysis showed proteinuria (774 mg/day) and increased fractional excretion of sodium (2.1%), potassium creatinine index (234 mEq/g; normal <13 mEq/g), and excretion of chloride (112 mEq/L; normal <20 mEq/L). The patient also showed increased excretion of calcium (9 mg/kg/day; normal <4) and β2 microglobin (1178 ng/ml; normal <300 ng/ml). The hemoglobin level reduced from 16 g/dl to 13.7 g/dl following IV hydration.

Ultrasonography revealed a small right and normal left kidney (59 mm and 81 mm, respectively) with increased echogenicity. Doppler sonography showed reduced peak systolic velocity (52 cm/sec at hilum) with prolonged acceleration time (0.15 sec), suggesting right main renal artery stenosis. Digital subtraction angiography confirmed narrowing of the main right renal artery that was partially corrected by percutaneous transluminal angioplasty [Figure 1]. Following angioplasty, two oral antihypertensive agents could be discontinued, and urine output declined to 2.8 ml/kg/hr by 2 weeks. At 1-month follow-up, blood levels of sodium (141 mEq/L) and potassium (4.4 mEq/L) were normal and there was decline in proteinuria (150 mg/day) and calcium excretion (4.6 mg/kg/day).
Figure 1: Digital subtraction angiography showing (a) occlusion of the main renal artery and reduced distal flow, and (b) improved flow after partial correction of stenosis by angioplasty

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  Discussion Top


We report a 2-year-old boy, symptomatic since infancy, with findings of polyuria, hypokalemia, asymmetric kidney size, and severe hypertension. A number of single-gene disorders including Liddle syndrome, glucocorticoid-remediable aldosteronism, apparent mineralocorticoid excess and rare variants of congenital adrenal hyperplasia, present with failure to thrive, hypokalemia, polyuria and hypertension. In addition, patients with apparent mineralocorticoid excess show hypercalciuria and mild nephrocalcinosis. The combination of hypokalemia and hyponatremia, metabolic alkalosis, solute diuresis, hypercalciuria and low molecular weight proteinuria is described in unilateral renovascular stenosis, termed the hyponatremic hypertensive syndrome.[3] It is proposed that activation of the renin–angiotensin system leads to hyperfiltration, with resultant glomerular and tubular dysfunction that resolves after percutaneous angioplasty. While the presence of hyponatremia and hypokalemia is well recognized in patients with renovascular hypertension, presentation with polyuria, failure to thrive, hypercalciuria, and nephrocalcinosis is rather uncommon.

Renovascular hypertension comprises 5%–10% of all childhood hypertension.[4] Takayasu arteritis is the chief etiology in older children, and fibromuscular dysplasia predominates below 5 years,[5],[6] sometimes with bilateral or intrarenal stenosis.[5] Features suggesting the diagnosis of renovascular hypertension in the present patient were severe hypertension requiring more than two antihypertensive agents and hypokalemic alkalosis. While fibromuscular dysplasia was considered most likely, the characteristic “string of bead” appearance on angiography was lacking.[5] Hyponatremic hypertensive syndrome is an uncommon presentation in children with unilateral renovascular disease and presents with variable symptoms[7] including neurological features of hyponatremia[8] or dehydration.[9]

The pathophysiology of the hyponatremic hypertensive syndrome involves stimulation of the renin–angiotensin–aldosterone axis due to ischemia of the affected kidney.[10],[11] The resulting elevation in arterial pressure causes pressure natriuresis though the contralateral normal kidney, leading to polyuria and hyponatremia. Volume depletion stimulates the release of antidiuretic hormone, aggravating hyponatremia and further release of renin.[10],[11] Aldosterone response to angiotensin II is heightened, with severe hypokalemia that further stimulates renin release;[10],[11] glomerular hyperfiltration, as in the present patient, may lead to nephrotic range proteinuria.[12] The pathogenesis of hypercalciuria and medullary nephrocalcinosis is not clear.[12] Polycythemia has also been reported in patients with hypertensive hyponatremia syndrome.[13]

Doppler ultrasonography is useful for screening for renovascular hypertension. Given the proportion of patients with intrarenal disease[4] and small vascular diameter, the sensitivity of noninvasive imaging to rule out renovascular disease is low in children. Digital subtraction angiography, thus, remains the gold standard for diagnosis.[14] The present report describes the association of renovascular hypertension with diffuse dysfunction of proximal and distal convoluted tubules, which mimic a primary tubular disorder. Amelioration of the stenosis, by angioplasty, resulted in better blood pressure control and reversal of metabolic abnormalities.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.



 
  References Top

1.
Bagga A, Bajpai A, Menon S. Approach to renal tubular disorders. Indian J Pediatr 2005;72:771-6.  Back to cited text no. 1
    
2.
Nussberger J. Investigating mineralocorticoid hypertension. J Hypertens Suppl 2003;21:S25-30.  Back to cited text no. 2
    
3.
Kovalski Y, Cleper R, Krause I, Dekel B, Belenky A, Davidovits M. Hyponatremic hypertensive syndrome in pediatric patients: Is it really so rare? Pediatr Nephrol 2012;27:1037-40.  Back to cited text no. 3
    
4.
Tullus K, Brennan E, Hamilton G, Lord R, McLaren CA, Marks SD, et al. Renovascular hypertension in children. Lancet 2008;371:1453-63.  Back to cited text no. 4
    
5.
Green R, Gu X, Kline-Rogers E, Froehlich J, Mace P, Gray B, et al. Differences between the pediatric and adult presentation of fibromuscular dysplasia: Results from the US registry. Pediatr Nephrol 2016;31:641-50.  Back to cited text no. 5
    
6.
Tullus K. Renovascular hypertension – Is it fibromuscular dysplasia or Takayasu arteritis. Pediatr Nephrol 2013;28:191-6.  Back to cited text no. 6
    
7.
Peco-Antić A. Pediatric hyponatremic hypertensive syndrome. Therapy 2005;2:301-9.  Back to cited text no. 7
    
8.
Ashida A, Matsumura H, Inoue N, Katayama H, Kiyohara Y, Yamamoto T, et al. Two cases of hyponatremic-hypertensive syndrome in childhood with renovascular hypertension. Eur J Pediatr 2006;165:336-9.  Back to cited text no. 8
    
9.
Gouyon JB, Bernardini S, Semama DS, Françoise M. Salt depletion and dehydration in hypertensive preterm infants. Pediatr Nephrol 1997;11:201-4.  Back to cited text no. 9
    
10.
Ivy JR, Bailey MA. Pressure natriuresis and the renal control of arterial blood pressure. J Physiol 2014;592:3955-67.  Back to cited text no. 10
    
11.
Nicholls MG. Unilateral renal ischemia causing the hyponatremic hypertensive syndrome in children – More common than we think? Pediatr Nephrol 2006;21:887-90.  Back to cited text no. 11
    
12.
Trivelli A, Ghiggeri GM, Canepa A, Oddone M, Bava G, Perfumo F. Hyponatremic-hypertensive syndrome with extensive and reversible renal defects. Pediatr Nephrol 2005;20:102-4.  Back to cited text no. 12
    
13.
Coulthard MG, Lamb WH. Polycythaemia and hypertension caused by renal artery stenosis. Arch Dis Child 2002;86:307-8.  Back to cited text no. 13
    
14.
Trautmann A, Roebuck DJ, McLaren CA, Brennan E, Marks SD, Tullus K. Non-invasive imaging cannot replace formal angiography in the diagnosis of renovascular hypertension. Pediatr Nephrol 2017;32:495-502.  Back to cited text no. 14
    


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