Nephrogenic Diabetes Insipidus: A Cause of Severe Nonobstructive Urinary Tract Dilatation
|Title:||Nephrogenic Diabetes Insipidus: A Cause of Severe Nonobstructive Urinary Tract Dilatation|
|Authors:||Stevens, Jim; Brown, Brad; McGahan, MD, John P.|
|Publisher:||Journal of Ultrasound in Medicine|
|Date Published:||July 01, 1995|
The following article is presented with the permission of the publisher for educational use within the NDI community. No part of this article may be reproduced in any way without permission in writing from the publisher.
This presentation of bilateral urinary tract dilation in the pediatric age group invokes a familiar differential diagnosis, including bladder outlet obstruction, reflux nephropathy, and primary megaureter. However, it is now well established that urine over-production can create a functional obstruction with secondary and often massive urinary tract dilation.
NDI is an established cause of urinary tract dilation. The first case of NDI associated with dilation of urinary tract was described by Waring and coworkers in 1945.1 The bulk of the literature describing the effects of NDI is found in the urologic and pediatric literature; very little has been written in imaging journals and texts regarding this diagnosis. We describe the ultrasonographic appearance of urinary tract effects of NDI.
FIGURE 1. Longitudinal ultrasonogram of the right kidney demonstrates marked pelvocaliectasis (arrows) secondary to high urine flow state. L, liver.
Radiologic evaluation at our facility included an initial ultrasonographic scan of the kidney at age 14 years, which demonstrated massive bilateral ureterectasis and pelvocaliectasis. The right kidney measured 13.4 cm and the left 13.9 cm. The renal cortices averaged approximately 5 mm in thickness.
RI (Pourcelot indices) at the interlobar arteries bilaterally ranged between 0.5 and 0.7. The bladder was significantly distended. A voiding cystourethrogram was performed shortly afterwards to exclude bladder neck obstruction (Fig. 3).
FIGURE 2. Longitudinal scan of the bladder (B) demonstrates right hydroureter. Left hydroureter also is present
Treatment in this patient includes hydrochlorothiazide, 50 mg bid, self-catheterization, and a low-salt diet. His course has been complicated by mild hypertension.
NDI is associated with poor reabsorption of water in the renal collecting ducts, resulting in both increased production and poor concentration of urine.2
FIGURE 3. Large capacity contract-filled bladder (B) extends superiorly above the pelvis.
Presenting age of congenital NDI may vary considerably. Our patient presented in infancy with vomiting. Early in life infants with NDI basically are not getting enough water, and thus they become hypernatremically dehydrated, causing vomiting. Long-standing mental retardation may occur, making timely diagnosis more urgent.2,4,5 Growth failure is seen often in infants with NDI because the baby is turning down formula and caloric intake for water.5 Later in life patients apparently adapt to their disease by increasing their fluid intake and commonly avoiding urination at an early age. This likely exacerbates the progressive dilation of the urinary tract.7
Initial radiographic evaluation of bilateral "hydronephrosis" should be thorough in the hope of discovering potentially correctable causative conditions. Ultrasonography, voiding cystourethrography, and reflux studies are all important modalities that should be considered. Urologic evaluation with cystoscopy and retrograde urethrography also may be needed to exclude subtle obstructive lesions. Causes of bilateral pelvocaliectasis and hydroureter include forms of hydronephrosis, such as bladder outlet obstruction from posterior urethral valves, severe reflux, or primary megaureter. NDI should be considered given the appropriate clinical presentation of imaging findings. Intrarenal RI values between 0.5 and 0.7 are indicative of nonobstructive dilation as elevated RI (>0.82) may be associated with physiologically significant upper urinary tract obstruction.8,9 Treatment of NDI usually is medical with thiazide diuretics, a low-salt diet, encouragement of frequent micturition, and indomethacin to lessen the progression of the dilation.2
Although most reports suggest that renal failure is rare, case reports of renal failure leading to dialysis exist.2,3,10 It is therefore extremely important to perform follow-up ultrasonography on a routine basis to evaluate for possible progression of the urinary tract dilation.
1. Waring AJ, Kajdi L, Tappan V: A congenital defect in water metabolism. Am J Dis Child 69:323, 1945
2. Zender HO, Ruedin P, Moser F, et al: Traumatic rupture of the urinary tract in a patient presenting nephrogenic diabetes insipidus associated with hydronephrosis and chronic renal failure: Case report and review of the literaure. Clin Nephrol 38:196, 1992
3. Nakada T, Miyauchi T, Sumiya H, et al: Nonobstructive urinary tract dilation in nephrogenic diabetes insipidus. Int Urol Nephrol 22:419, 1990
4. Ten Bensel RW, Peters ER: Progressive hydronephrosis, hydroureter, and dilation of the bladder in siblings with congenital nephrogenic diabetes insipidus. J Pediatr 77:439, 1970
5. Linshaw MA, Stapleton FB, Knapp J: Growth failure: Nephrogenic diabetes insipidus. J Kans Med Soc 78:345, 1977
6. Tank ES, Alexander SR, Craven RM: Polyuric megalocystis. J Urol 124:692, 1980
7. Wiggelinkhuizen MB, Retief PJ, Wolff B, et al: Nephrogenic diabetes insipidus and obstructive uropathy. Am J Dis Child 126:398, 1973
8. Gilbert R, Garra B, Gibbons MD: Renal duplex Doppler ultrasound: An adjunct in the evaluation of hydronephrosis in the child. J Urol 150:1192, 1993
9. Fung LC, Steckler RE, Khoury AE, et al: Intrarenal resistive index correlates with renal pelvis pressure. J Urol 152(2 Pt 2):604, 1994
10. Streitz JM Jr, Streitz JM: Polyuric urinary tract dilation with renal damage. J Urol 139:784, 1988
Received November 22, 1994, from the Department of Radiology, David Grant Air Force Base, Travis, California (J.S.) , and the Department of Radiology, University of California, Davis, Sacramento, California (B.D.B., J.P.M.)
Address correspondence and reprint requests to John P. McGahan, MD, Department of Radiology, UC Davis Medical Center, 2516 Stockton Blvd., Sacramento, CA 95816
This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)
NDI is associated with poor reabsorption of water in the kidneys' collecting ducts which results in increased production of dilute (poorly concentrated) urine. NDI may be acquired due to some obstruction of the urinary tract and, if this is the case, clearing the obstruction will correct the NDI. It may be caused by some drugs such as lithium that are used as part of a therapeutic procedure. Discontinuing the lithium generally reverses the NDI. However, NDI may also be inherited. If so, though it may be modified somewhat with hydrochlorothiazide and a low salt, low protein diet, there is, as yet, no cure.
Stevens, et al., report on a 15 year-old boy with congenital NDI manifesting shortly after birth. At 14, he had his urinary tract examined with ultrasound and it was found to be massively distended: both ureters (the tubes connected to the bladders through which urine is voided) and the collecting cups in the kidneys' pelvic region were distended. Two follow-up kidney ultrasonic scans when the patient was 15 revealed that his kidneys had dilated further, though the rest of the urinary tract had not.
Steven's, et al., encourage thorough evaluation of patients who show distention in both kidneys. The evaluation should include ultrasonic and x-ray scans along with tests for the possibility that the distention is caused by a backwards flow of the urine. This will help determine if there is any physical obstruction that can be corrected. And, of course, there should be a diagnosis for NDI, especially if no physical obstruction is found. If NDI is diagnosed, it is extremely important to perform follow-up ultrasonography on a routine basis to evaluate for possible progression of urinary tract dilation in order to monitor the possibility of kidney failure.