In the context of conservative management of pediatric nepholithiasis
(1), we are curious about how is 60 mL/kg per day derived? The basic
calculation for maintenance fluid requirement, based on patient weight, is
determined as 100 mL per kg for first 10 kg, 50 mL per kg for next 10 kg,
and 20 mL per kg for each kg above 20 (2). Since most affected children
are below 2 years old with body weight of lower than 13 kg, we assume that
more fluid should be given in addition to maintenance to get adequate
hydration. It is hard to know whether a child is adequately hydrated.
Herein, we recommend an objective method to monitor the hydration status
by recording urine output. For infants, small children below five years of
age, and greater than 5 years of age, the urine output per day is
suggested to be higher than 750 mL, 1000 mL, and 1500 mL, respectively
(3). Therefore, the first therapy used in any child with nephrolithiasis
is increased fluid intake to maintain a targeted 24-hour urine volume
based upon the age of the child.
Furthermore, we wonder if intravenous alkalization by 5% NaHCO3
solution is necessary in all cases. Alkalization of the urine with
administration of sodium citrate or sodium bicarbonate will increase the
solubility of uric acid. However, it is commonly employed for those
refractory to increased fluid intake or for preventing uric acid
precipitation in adults (4). We speculate that more conservative treatment
for asymptomatic children may decrease their sufferings and reduce health
care expenditures. From our experience, most patients passed their stones
by taking 1000 to 1500 ml fluid each day orally and increasing fruits and
vegetables intake without intravenous hydration and alkalization. Urine PH
was followed to monitor if the oral alkalization by fruits and vegetables
was sufficient. This safe and conservative management is widely accepted
and easily cooperated by parents of the affected children.
The author reported that renal stones were disappeared in 3 to 5 days
in all cases. Within such a short time, all children had resolution of
their stones. These findings would benefit from discussion. In our
experience, it took from 1 to 3 months for the resolution of the stones
(Table 1 below). Their rapid resolution in the study of Zhu et al. does
raise questions regarding interpretation of the ultrasonographic findings.
We wonder if the sensitivity of the B-ultrasonography can be that high to
detect the stone as small as 0.9 x 0.8 mm (Patient No. 5 and 6). It is
reported that the sensitivity of ultrasonography can reach as high as 81%
(5). For the stones smaller than 1.0 mm, however, the validity should be
questioned. Clarification would be helpful and would support the validity
of the findings as stone material.
I-Jen Wang,1,2 Chih-Jung Chen,3 Pau-Chung Chen4
1 Taipei Hospital, Department of Health
2 China Medical University
3 Hualien Hospital, Department of Health
4 National Taiwan University, Taipei, Taiwan
References
1. Sheng-lang Zhu, Jiu-hong Li, Lu Chen, Zhong-xian Bao, Long-jiang
Zhang, Jia-ping Li, Jie-hui Chen, and Kun-mei Ji. Conservative Management
of Pediatric Nephrolithiasis Caused by Melamine-Contaminated Milk Powder.
Pediatrics 2009; 123(6): e1099-e1102.
2. Anthony J Alario. Practical Guide to the Care of the Pediatric
Patients. 1se ed. St. Louis, NJ: Mosby, Inc; 1997.
3. Milliner DS. Urolithiasis. In: Pediatric Nephrology, 5th ed,
Avner, ED, Harmon, WE, Niaudet, P, Lippincott Williams and Wilkins,
Philadelphia 2004. p.1091.
4. Jodi Smith, F Bruder Stapleton. Prevention of recurrent
nephrolithiasis in children. 2008. (Accessed June 15, 2009 at
http://www.utdol.com/online/content/topic.do?topicKey=pedineph/18549&selectedTitle=4~150&source=search_result)
5. Ather MH, Jafri AH, Sulaiman MN. Diagnostic accuracy of
ultrasonography compared to unenhanced CT for stone and obstruction in
patients with renal failure. BMC Med Imaging 2004; 4(1):2.
Table 1. Resolution of the stones for children in Taiwan
Age(y/o)/Gender; Stone size(mm)/Follow-up
2 F ; 3.0 / F/U 3 m disappear
4.4 M ; 7.5 / F/U 1 m 5.5mm,F/u 3 m disappear
4.8 F ; 4.5 / F/U 1 m disappear
1.7 M ; 3.2 / F/U 1 m disappear
1.3 F ; 4.5 / F/U 1 m 4mm,F/u 3 m disappear
2 M ; 2.3 / F/U 3 m disappear
2.9 F ; 2.1 / F/U 3 m disappear
2 M ; 3.0 / Loss F/U
2 M ; 2.6 / F/U 3 m disappear
4 F ; 3.2 / F/U 3 m disappear
2.5 F ; 3.8 / F/U 1 m 3.5mm,F/u 3 m disappear
3 M ; 4.0 / Loss F/U
9 F ; 5.0 / Loss F/U
1.9 F ; 3.3 / Loss F/U
* F/U, Follow-up; m, months
Conflict of Interest:
None declared
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