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Saudi Journal of Kidney Diseases and Transplantation
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CASE REPORT  
Year : 2016  |  Volume : 27  |  Issue : 6  |  Page : 1239-1241
Failure to thrive and nephrocalcinosis due to distal renal tubular acidosis: A rare presentation of pediatric lupus nephritis


Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India

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Date of Web Publication28-Nov-2016
 

   Abstract 

A 9-year-old female child was initially diagnosed of having nephrocalcinosis with distal renal tubular acidosis (dRTA) while investigating for short stature. She later on developed features of nephrotic syndrome (NS) while on treatment for RTA. Investigation for the cause of NS revealed very strong serological evidence in favor of systemic lupus erythematosus (SLE). Histopathological confirmation could not be done due to bilateral severely contracted kidneys. There are a few case reports of dRTA as the presentation of SLE, but nephrocalcinosis with dRTA with subsequent manifestation of SLE has hitherto not been reported in literature.

How to cite this article:
Nandi M, Das MK, Nandi S. Failure to thrive and nephrocalcinosis due to distal renal tubular acidosis: A rare presentation of pediatric lupus nephritis. Saudi J Kidney Dis Transpl 2016;27:1239-41

How to cite this URL:
Nandi M, Das MK, Nandi S. Failure to thrive and nephrocalcinosis due to distal renal tubular acidosis: A rare presentation of pediatric lupus nephritis. Saudi J Kidney Dis Transpl [serial online] 2016 [cited 2020 Jan 22];27:1239-41. Available from: http://www.sjkdt.org/text.asp?2016/27/6/1239/194679

   Introduction Top


Nephrocalcinosis and failure to thrive (FTT) could be a presenting feature of distal renal tubular acidosis (dRTA). [1],[2] Rarely, certain immune-mediated disorders such as systemic lupus erythematosus (SLE) and Sjögren's syndrome may give rise to dRTA when renal tubulointerstitial tissue is involved. [3],[4],[5],[6],[7] However, it is highly unusual for a patient of SLE presenting with the clinical manifestations of tubular involvement without any clinical or biochemical features of glomerular involvement. We could find only one such report in a child where dRTA had preceded the diagnosis of SLE. [7] Here, we report a child who revealed having dRTA with bilateral nephrocalcinosis during investigations for short stature. She subsequently developed features of nephrotic syndrome (NS), investigation for which revealed serological evidence of lupus nephritis.


   Case Report Top


A 9-year-old female child presented with the complaint of not gaining adequate height and weight for the last four years. She also had anorexia and generalized weakness but no fever or any bladder or bowel problems. Past and family histories were noncontributory. She had normal facies, blood pressure of 90/60 mm Hg, respiratory rate of 32/min, and no edema, pallor, or lymphadenopathy. Her height was 114 cm and weight was 12 kg (height for age, weight for age, and weight for height <3 rd percentile). Mid-parental height was 166 cm (between 10 th and 25 th percentile). Sexual maturity staging was Tanner Stage I. Examination of other systems did not reveal any abnormality.

On investigations, bone age was four years, hemoglobin level 10.4 g/dL, total leukocyte count 9600/mm 3 (N54, L43, E3), platelet count 155,000/mm 3 , and erythrocyte sedimentation rate 22 mm 1 st h. Her serum Na + was 141 mmol/L, K + 3.61 mmol/L, serum albumin 2.6 g/dL, and serum globulin 3.5 g/dL. Liver enzymes showed normal values. Urine had trace of albumin but no red blood cell or cast. Spot protein-creatinine ratio was 0.18. Chest skiagram was normal. Blood urea was 31 mg/dL, creatinine 1.0 mg/dL, and estimated glomerular filtration rate 63 mL/min (Stage II chronic kidney disease). She had normal thyroid profile and blood sugar. Ultrasonography showed bilateral small contracted kidneys (right 4.92 cm, left 4.26 cm in largest diameter) with nephrocalcinosis at corticomedullary regions [Figure 1] and [Figure 2] without obstructive uropathy. Total serum calcium was 9.6 mg/dL, spot urinary calcium-creatinine ratio 0.4 (n <0.2), and 24 h urinary calcium excretion 68 mg (n <4 mg/kg). Arterial blood gas (ABG) showed compensated hyperchloremic metabolic acidosis with normal anion gap (ABG: pH 7.31, PCO 2− 22.8, HCO 3− 15, Cl 117, anion gap 12). Urinary pH was 6.3 with positive urinary anion gap (urinary Na + + K + − Cl = 80 + 6.4 − 67 = 19.4 mEq/L).
Figure 1: Ultrasonography kidney-ureter-bladder showed nephrocalcinosis with small and contracted right kidney.

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Figure 2: Ultrasonography kidney-ureter-bladder showed nephrocalcinosis with small and contracted left kidney.

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She was put on low-dose oral alkali supplementation (sodium bicarbonate tablets at 150 mg/kg/day equivalent to 185 mEq/kg/day) and was discharged from the hospital with advice for regular follow-up. One month after discharge, she developed oliguria with facial puffiness and swelling of the feet. Investigations at this point revealed +++ albuminuria, spot urinary protein-creatinine ratio 2.5, blood urea 36 mg/dL, and creatinine 1 mg/dL; serum albumin was 1.9 g/dL and cholesterol 256 mg/dL. Serum C3 level was 46.7 mg/dL (N = 90-180) and C [4] 11 mg/dL (N = 10-40). Anti nuclear antibody (ANA) was positive in 1:160 dilution, speckled pattern (Hep-2 method). Antidouble-stranded DNA (dsDNA) titer was positive by immunofluorescence method. Hence, based on the features of NS with heavy proteinuria, positive ANA and anti-dsDNA antibody, and low C3, a diagnosis of SLE with nephritis was made. Renal biopsy was not attempted as her kidneys were too contracted to give any useful information, and also, the risk would have outweighed the possible benefits as also opined by the nephrologists of our institute

With a diagnosis of lupus nephritis with nephrocalcinosis and dRTA, she was given oral daily prednisolone and monthly pulse intravenous cyclophosphamide (6 pulses) along with alkali therapy. Prednisolone was given initially at dose of 2 mg/kg with gradual tapering after six weeks. Now, she is maintained on 0.2 mg/kg dose. Monthly boluses of cyclophosphamide were given at the dose of 500mg/m 2 . She has improved clinically, biochemically, and serologically with this treatment. She has gained 5 cm in height and 7 kg in weight, acidosis has improved, urinary calcium-creatinine ratio is 0.05, serum C3 and C4 have normalized (121 mg/dL and 35.2 mg/dL, respectively), and dsDNA has become negative at the end of eight months of therapy. The dose of bicarbonate was adjusted according to the requirement as judged by ABG analysis periodically. The requirement was found to be gradually reducing and after eight months bicarbonate could be stopped without affecting normal ABG status in follow-up.


   Discussion Top


dRTA is due to inability of the distal tubule to establish an adequate pH gradient between plasma and the distal tubular fluid. These patients have tendency to develop growth retardation, nephrocalcinosis, and renal calculi. [1],[2] Here, growth retardation and nephrocalcinosis were clue to investigate for dRTA.

Some identifiable autoimmune causes of dRTA are Sjögren's syndrome, [6] systemic lupus erythematosus (SLE), and rheumatoid arthritis. [2] Bagga et al reported a pediatric case report of dRTA with SLE in a 10-year-old female child where dRTA had preceded the manifestations of SLE by four years. [7]

Our patient had bilaterally contracted kidneys with diffuse nephrocalcinosis and FTT which was suggestive of long-standing dRTA. Subsequently, she developed NS with serological features of SLE. Histopathological confirmation could not be done due to gross contraction of kidneys with nephrocalcinosis. Thus, she was given a diagnosis of lupus nephritis based on serology only. The clinical features and serology were responded to the immunosuppressive treatment given. In this child, dRTA seems to be a part of SLE occurring antecedent to NS which is typical and more common manifestation of lupus nephritis. Improvement of biochemical abnormalities of RTA also in response to immunosuppressive medications for SLE substantiates this fact.

It is known that kidneys are the most common organs to be involved in SLE. Renal involvement mainly occurs in the form of nephritis or NS or asymptomatic hematuria/ proteinuria. However, dRTA with nephrocalcinosis and growth retardation without any of these common features as initial presentation of SLE is rare.

This report is an effort to highlight one more mode of presentation of SLE, an addition to the long list of myriad of presentations.

Conflict of interest: None declared.

 
   References Top

1.
Bagga A, Sinha A. Tubular disorders. In: Srivastava RN, Bagga A, eds. Pediatric Nephrology. 5th ed. New Delhi: Jaypee Brothers; 2011. p. 302-9.  Back to cited text no. 1
    
2.
Jha R, Muthukrishnan J, Shiradhonkar S, Patro K, Harikumar K, Modi KD. Clinical profile of distal renal tubular acidosis. Saudi J Kidney Dis Transpl 2011;22:261-7.  Back to cited text no. 2
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3.
Ter Meulen CG, Pieters GF, Huysmans FT. Flaccid paresis due to distal renal tubular acidosis preceding systemic lupus erythematosus. Neth J Med 2002;60:29-32.  Back to cited text no. 3
    
4.
Gera C, Mohapatra D, Calton N. Hypokalaemic paralysis secondary to distal renal tubular acidosis as the presenting symptom of systemic lupus erythematosus. Singapore Med J 2011;52:e1-3.  Back to cited text no. 4
    
5.
Ray S, Pillai MG, Kurian G, Unni VN. Latent systemic lupus erythematosus presenting as hypokalemic paralysis. Indian J Nephrol 2005; 15:98-100.  Back to cited text no. 5
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6.
Bastani B, Haragsim L, Gluck S, Siamopoulos KC. Lack of H-ATPase in distal nephron causing hypokalaemic distal RTA in a patient with Sjögren's syndrome. Nephrol Dial Transplant 1995;10:908-9.  Back to cited text no. 6
    
7.
Bagga A, Jain Y, Srivastava RN, Bhuyan UN. Renal tubular acidosis preceding systemic lupus erythematosus. Pediatr Nephrol 1993;7: 735-6.  Back to cited text no. 7
    

Top
Correspondence Address:
Madhumita Nandi
Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal
India
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DOI: 10.4103/1319-2442.194679

PMID: 27900972

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    Abstract
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