Objective: In order to establish some preliminary data of our population, we determined the ultrasonographic kidney dimensions in individuals withoud known renal disease. We assessed whether age, sex, side, body mass index (BMI) and presence or absence of diabetes mellitus and hypertension affect the renal size. Methods: Ultrasonographic kidney measurements were performed on 194 adult patients without known kidney lesions. Measurements included length, width, cortical thickness and estimation of renal size which was obtained by multiplying the first three variables. The effect of age, gender, side, height, weight, BNll, hypertension and diabetes mellitus was statistically analyzed. Results: The mean kidney length was 10.4 ±0.8 cm, mean with 4.5 + 0.6 cm and mean cortical thickness 1.6 ± 0.2 cm. The estimated mean renal size was 76 ±22 cm3. Kidney length did not significantly differ between zight and left, however, kidney width, cortical thickness and size did (p\u3c0.05). Right kidneys were smaller than the left ones. In univariate analysis, the mean renal size correlated with age, sex, side, BMI and absence or presence of hypertension and diabetes mellitus. In a multivariate analysis, however, the only significant factors affecting renal size were sex and BMI. Conclusion: We conclude that renal size is related to age, side, sex and the individual’s height and weight. the normal values for the Pakistani population Population-based studies are needed to establish (JPMA 50:12, 2000)

Abbas, Farhat

Afzal, Masood

Biyabani, Syed Raziuddin

Buchholz, Niels-Peter

Javed, Qaiser

Rizvi, Imtiaz

Talati, Jamsheer Jehangir

eCommons@AKU

eCommons@AKUSection of Urology Department of SurgeryJanuary 2000Ultrasonographic renal size in individuals withoutknown renal disease.Niels-Peter BuchholzAga Khan UniversityFarhat AbbasAga Khan UniversitySyed Raziuddin BiyabaniAga Khan UniversityQaiser JavedAga Khan UniversityJamsheer TalatiAga Khan UniversitySee next page for additional authorsFollow this and additional works at: http://ecommons.aku.edu/pakistan_fhs_mc_surg_urolPart of the Surgery Commons, and the Urology CommonsRecommended CitationBuchholz, N., Abbas, F., Biyabani, S. R., Javed, Q., Talati, J., Afzal, M., Rizvi, I. (2000). Ultrasonographic renal size in individualswithout known renal disease.. Journal of the Pakistan Medical Association, 96(1), 12-16.Available at: http://ecommons.aku.edu/pakistan_fhs_mc_surg_urol/37AuthorsNiels-Peter Buchholz, Farhat Abbas, Syed Raziuddin Biyabani, Qaiser Javed, Jamsheer Talati, Masood Afzal,and Imtiaz RizviThis article is available at eCommons@AKU: http://ecommons.aku.edu/pakistan_fhs_mc_surg_urol/37Ultrasonographic Renal size in Individuals without known RenalDiseaseNiels-Peter Buchholz,Farhat Abbas,Syed Raziuddin Biyabani,Qaiser Javed,Jamsheer Talati ( Departments of Surgery(Section of Urology), The Aga Khan University. Karachi. ) Masood Afzal,lmtiaz Rizvi ( Departments of Radiology, The Aga Khan University. Karachi ) Abstract Objective: In order to establish some preliminary data of our population, we determined theultrasonographic kidney dimensions in individuals withoud known renal disease. We assessed whetherage, sex, side, body mass index (BMI) and presence or absence of diabetes mellitus and hypertensionaffect the renal size.Methods: Ultrasonographic kidney measurements were performed on 194 adult patients withoutknown kidney lesions. Measurements included length, width, cortical thickness and estimation of renalsize which was obtained by multiplying the first three variables. The effect of age, gender, side, height,weight, BNll, hypertension and diabetes mellitus was statistically analyzed.Results: The mean kidney length was 10.4 ±0.8 cm, mean with 4.5 + 0.6 cm and mean corticalthickness 1.6 ± 0.2 cm. The estimated mean renal size was 76 ±22 cm3. Kidney length did notsignificantly differ between zight and left, however, kidney width, cortical thickness and size did(p<0.05). Right kidneys were smaller than the left ones. In univariate analysis, the mean renal sizecorrelated with age, sex, side, BMI and absence or presence of hypertension and diabetes mellitus. In amultivariate analysis, however, the only significant factors affecting renal size were sex and BMI.Conclusion: We conclude that renal size is related to age, side, sex and the individual’s height andweight. the normal values for the Pakistani population Population-based studies are needed to establish(JPMA 50:12, 2000).Introduction The kidney size of a patient is a valuable diagnostic parameter in urological and nephrologic practice.While the leading anatomy text describes the adult kidney as 12 cm long, 6 cm wide and 3 cm deep1,further review of the literature shows that renal size varies with age, gender, body mass index,pregnancy and co-morbid conditions2,3. Renal size may be an indicator for the loss of kidney mass andtherefore, kidney function2,3. It is valuable in monitoring unilateral kidney disease through comparisonwith the other, compensatorily increased side4 and for the discrimination between upper and lowerurinary tract infections9. Renal infections/inflammations, nephrologic disorders, diabetes mellitus andhypertension are the most important co-morbid conditions affecting renal size4-9,5,16Since the renal size is affected by various factors, it is necessary to first establish the normal values.The information available in the West may not be extrapolated to our population since the renal sizemay differ between ethnic groups and according to body size11,17-19. While population-based studiesare needed to establish the normal values for Pakistani individuals, in our study we determined theultrasonographic renal size in a group of individuals with no known renal disease and assessed theeffect of age, gender. side and BMI. In addition, we assessed the effects of hypertension and diabetesmellitus in a subgroup of our patients on renal size and compared our findings with the literature.Subjects and Methods For this prospective study, 201 consecutive patients between 13 to 80 years of age. who underwent anabdominal diagostic ultrasound at the Department of Radiology of the Aga Khan University Hospital,Karachi between August 1997 and March 1998, had an additional screening and measurements of thekidneys. Pregnant patients, patients with known kidney or urinary stone diseases and patients with anultrasound for the diagnosis of lumbar or urinary symptoms were excluded. Seven additional patientswere excluded due to incomplete data to leave 194 study patients.The kidney dimensions measured include length (distance pole to pole), width (transversal axis) andcortical thickness, in millimeters. We estimated the kidney size, defined as length x width x corticalthickness, which correlates closely to the renal volume. All ultrasounds were performed by oneexperienced radiologist to exclude inter-observer variation. Additional data recorded either atpresentation or at subsequent telephonic contact include age, gender. height, weight, BMI (weight[kg]/height [meter2]) and history of estblished hypertension and diabetes mellitus. Data were entered ina Microsoft ExcelR database and statistically analyses using SPSS Version-8. Comparative analyseswere done by means of a student\'s "t" test. A p-value <0.05 was regarded as statistically significant.Results Of the total 194 patients, 98 were males and 96 females. The mean age was 44.7 ± 14 years (range 13-80); 46.1 ±, 15.4 years (13-80) for males and 43.3 ± 13.2 years (15-80) for females.Renal size and effect of gender and side: The mean kidney length was 10.4 ±. 0.8 cm (7.9 - 12.3), themean kidney width 4.5±0.6cm (3.3 - 6.3) and the mean cortical thickness 1.6 ± 0.2 cm (I . 1 - 2.0).Kidney size (length x width x cortical thickness) was 76.16 ± 21.7 cm3 (36.8 - 138).There was no significant difference in kidney length between right and left side (P<0.06). Howevei;differences in width, cortical thickness and size were all significant (P<0.05), with the right kidneybeing significantly smaller than the left (Table 1).As a group, female kidneys were significantly smaller than the male kidneys (Table 2).Renal size and effect of age: In our study, there were 9 individuals in their 2nd decade of life, 23 in the3rd, 48 in the 4th, 52 in the 5th, 32 in the 6th, 22 in the 7th and 8 in the 8th decade of life. All renaldimensions increased with age till the 3rd decade, remained more or less stable through the middle age,then declined beyond the 6th decade (Table 3; Figure 1).Renal size and effect of body mass index:Information on body mass index (BM1) (weight [meter]2) was available in 118 study patients whowere then divided into 3 groups, i.e., BMI 10-20, 21-30 and 31-40. The mean renal size correlated wellwith BMI and correspondingly increased with BMI. This observation, however, was not made for theright kidney in the 31-40 BMI group (Figure 2).Renal size in hypertensives versus non-hypertensives and diabetics versus non-diabetics: Informationabout the absence or presence of established hypertension or diabetes mellitus was available in 118individuals.Table 4 shows that the mean renal size in both sides was smaller in hypertensive individuals whencompared with  non-hypertensives, but the difference was statistically insignificant. Similarly, diabeticshad larger kidneys than non-diabetics, but the difference was insignificant. Since BMI could be animportant confounding factor in this analysis, we compared the groups again in BMI matchedindividuals (Table 5)and except for the left kidney dimensions in hypertensive versus non-hypertensive individuals, thehypertensive kidneys were smaller and diabetic kidneys were larger.Multivariate Analysis: We finally performed a linear regression analysis to assess the effect of thevariables studied on renal size. Only BMI and sex of the individual independently influenced thekidney size on both sides. Both, hypertension and diabetes mellitus, which on univariate analysis hadshown significant influence on renal size, were non-significant in the multivariate analysis (Table 6).Discussion The normal size of a kidney is variable and is affected by age, gender, BMI, as well as the side. Thesize provides a rough indication of the renal function. The minimal size of a fully functional kidney is 9cm in length2. Decrease of size and function are seen with chronic renal failure4, renal arterialocclusion2 and late stage renal venous thrombosis5. However, although kidney size seems to be relatedto a number of vascular diseases, there is no correlation with blood pressure20. Physiologically, renallength decreases 0.5 cm per decade after middle age11-3.On the other hand, there is an increase in kidney size in early stage renal thrombosis5, early stagediabetes mellitus7,8 and renal inflammation6. A physiological increase of glomerular filtration rate andkidney size can be observed in pregnancy10. Kidney size also increases with increased protein intake inmice21.In order to estimate aberrations of kidney size, normal values must be established first. Not manystudies have been done on this issue. There are, as far as we know, no reliable reference tables becausethe measurements vary between men and women, between people of different ethnic backgrounds andeven between kidneys of the same individual. Also, it has to be borne in mind that kidney sizemeasurements with ultrasound (US), as well as with CT and MRI result in a 24% underestimation ofthe renal value22.Commonly, US is used to screen and measure the kidney. In comparison with an intravenouspyelogram, US is more accurate and suffers neither from the geometric magnification of X-raying, norfrom a possible increase in kidney size by osmotic diuresis through iodinated contrast material23. It hasbeen analyzed as a reliable, repeatable (inter-observer variation) and reproducible (intra-observervariation) method24. In our study, a single senior radiologist carried out the measurements atpredetermined fixed points, to minimize the inter-observer and intra-observer variation. Studies onkidney length and size have also been made by means of CT25 and MRI22. But although these methodsshow, not unexpectedly, a better repeatability22, we believe that US is the tool of first choice due to itsubiquitous availability, its easy handling and its cost-effectiveness.Most studies have looked at kidney length. Ultrasonic kidney length measurement (bi-polarmeasurement) is the most commonly used and most practical measurement in clinical practice10 and iscorrelated to renal function3.Normal renal length varies from 100 to 124 mm in different populations17-19,25 dependent on ethnicbackground, side and sex. While population-based studies are needed to establish the normal values forPakistani individuals, our pilot study group showed a mean kidney length of 104 mm. This is at thelower end of the scale and together with a Malaysian study population19 is probably a reflection of therelatively small body size of most IndoAsians. Organ size is unquestionably related to the body size.Accordingly, Africans figured in the upper range 17 and Caucasians somewhere in the middle25.In our study, the kidney length, width, cortical thickness and size were significanly larger in males thanin females. This has been reported by other investigators17,19,26 and has been related to differences inbody size26. We found this difference significant even in the multivariate analysis.Throughout all studies, there is a marked but not significant difference of kidney length between theright and left side, with the left side being on an average 5% larger11,17,19. We feel it could be related tothe hepatic mass which does not allow comparable vertical growth of the right kidney to that which isattained by the left kidney. In our study, except for the length, all other renal dimensions weresignificantly larger on the left than on the right side. We thus feel that instead of renal length the renalsize as determined by us, or volume as assessed by others, may be used as the most useful parameterfor evaluation and comparison.The age of an individual has an important bearing on the kidney size. We found that the kidney sizeincreases till the 3rd decade, remains stable through the middle age and then declines’ We havedeveloped a prototype reference table of age and renal dimensions for both sides, as there is no suchinformation available for our population. The validity of this information, however, needs to beestablished through larger, population-based studies. Such a reference table is extremely useful forroutine evaluations and monitoring of urological and nephrologic diseases.Our data shows a strong correlation between renal size and BMI (Figure 2). The renal size increasedcorrespondingly with an increasing BMI, except for the right kidney in the group of obese individuals(BMI:3 1-40). In these patients, the body mass increase may surpass the renal growth capacity. Also, ithas to be considered that gross obesity can be one of the limitations of ultrasound examination. Otherinvestigators have also shown a strong correlation of renal volume with height, weight andBMI11,13,17,19We assessed the effect of hypertension and diabetes mellitus on renal size because of the frequentaffection of our adult population with these co-morbid conditions. While in the univariate analysis,both hypertension and diabetes mellitus were significant factors affecting renal size, their effect was notsignificant in multivariate analysis. It has previously been shown that high blood pressure is notproportionally related to kidney size20. In long-standing hypertension, however, the kidney size isshown to decrease due to ischemic changes with resultant fibrosis and hyalinization27. Otherinvestigators have related an increase in kidney size with an increased glomerular filtration rate in earlystage diabetes niellitus. This increase represents indeed a risk factor for diabetogenic nephropathy thusmaking ultrasonic kidney measurement a tool for the diagnostic and prognostic assessment of diabeticpatients7,8.Finally, of all the variables assessed in our study, the most significant factors associated with the kidneysize were sex (p=0.000) and BMI (p=0.01, 0.004) in the linear regression analysis model.In summary, normal values for kidney measurements are dependent on age, sex and body mass index.This has to be considered by the ultrasonographer. Aberrations from these values can give valuablegeneral clues and confirmations in the diagnosis of particular diseases. A slightly small right kidneymay be considered as normal and a reference table as developed by us can be used for routineevaluation. For the Pakistani population, normal kidney measurement values need to be developed bymeans of population-based studies.Reference 1.Grays Anatomv. 38th ed, U.K. Churchill Livingstone, 1995.2.Shcherbak Al. Angriographic criteria in the determination of indications for organ preserving surgeryin renal artery occlusion. Klin. Khir., 1989; 2: 53.Guzman RP, Zierler RE, Isaacson JA, el al: Renal atrophy and arterial stenosis. A prospective studywith duplex ultrasound. Hypertension. 1994:23:346-47.4.Yamaguchi S. Fujii H, Kaneko S. et al. Ultrasonographic study in patients with chronic renal failure.Part 1. Ultrasonic measurement of renal size and analysis of renal ultrasonotomograms. NipponHinyokika Gakkai Zasshi, 1990;81: 1175-77.5.Montague JP, Neuenschwander S, Duguet-Lannes MD, et al. Renal venous thrombosis in infants.Ultrasonic findings in 7 cases. Arch. Fr. Pediatr., 1982;39:67-68.6.Hiraoka M. 1-Ion C, rsuchida S, et al. Ultrasonographic findings of acute tubulointerstitial nephritis.Am. J. Nephrol., 1996:16:154.7.Tuttle KR, Bruton JL., l’erusek MC. et al. Effect of’ strict glycemic control on renal hemodynamicresponse to amino acids and reital enlargement in insulin-dependent diabetes uncllitus. N. EngI. J.Med., 1991;324:1626-29.8.Sehwieger J, Fine LG. Renal hypertrophy. growth factors and neprhopathy in diabetes mellitusSemin. Nephrol., 1990:10:242-43.9.Dinkel E, Ortit S, Dittrich M, ct al. Renal sonography in the differentiation of upper front lowerurinary tract infection. Am. i. Roentgenol.. 1986; 146:775-777.10.Christensen T, Klebe JG, Bertelsen V. et at. Changes in renal volume during normal pregnancy.Acta. Obstet. Gvnecol. Scand., 1989;68:541-43.11.Emamian Sa, Nielsen MB. Pedersen iF, et al. Kidney dimensions at sonography. Correlation withage, sex and habitus in 665 adults volunteers. Am. J. Rocntgenol., 1993:160:83.84.12.Meyer BR. Renal function in aging. J. Am. Geriatr. Soc.. 1989;37:791-92.13.McLachlan M. Wasserman P. Changes in sizes and distensibility of’ the aging kidney: Br. J. Radiol.,1981:54:488.l4.Josephson S. Larsoon F. Experimental partial ureteric obstruction in newborn rats. VIII.Coutralateral kidney weight after release of the obstruction. Urol. Int., 1996;57: 135-37.15.Paivansato-MJ, Merikanto-J.. Savolainen-M.l et al. Effect of’ hypertension, diabetes and oiliercardiovascular risk factors on kidney size in middle aged adults. Clin Nepltrol., 1 998;50: 161-68.16.Yamada-H Hishida-A, Kumagai-H. et al. Effects of’ age. renul diseases and diabetes mellitus on therenal size reduction accompanied by the decrease of renal function. Nippon-Jinzo-Gakkai-Shi.,1992:34:1071-75.17.Odita JC. Ugbodaga Cl. Roentgenologic estimation of kidney size in adult Nigerians. Trop. Geogr.Med., 1982:34: 177-79.18.Sainpaio EJ. Mandarun de Lacerda Ca, Morphometry of the kidney. Applied study in urology andimaging. J. Urol. Paris.. 989:95:77-78.19.Wang F, Cheok SP. Kuan BB. Renal size in healthy Malaysian adults by ultrasonography. Med. J.Malaysia, 1989:44:45-46.20.Raunan GV, Clark A. Campbell S.et al. Is blood pressure related to kidney size and shape? Nephrol.Dial. Transplant, 1998:13 728.21.Hammond KA, lanes DN. The effect of increased protein intake on kidney size and function. J. Exp.Biol. 1998:21)1:2081-82.22.Bakker J, Olree M, Kaatee R. et al. lit vitro measurement of kidney size. Comparison ofultrasonography and MRI. ultrasound Med. Biol., 1998;24:683-84.23.Brandt TD, Neiman HL, Dragowski Mi. et al. Ultrasound assessment of normal renal dimensions. J.Ultrasound Med., 1982:1:49-51.24.Ablett MJ, Coulthard A, Lee RE, et al. I-low reliable are ultrasound measurements of renal length inadults? Br. J. Radiol., 1995:68:1087-89.25.Gremigni D, Todescan GC, Giannardi G, et al. Renal volume and human somatic type. Boll Soc.Ital. Biol, Sper., 984:60:887-88.26.Miletic D, Fuckar 7 Stistic A, et al, Sonographic measurement of absolute and relative renal lengthin adults. J. Clin. Ultrasound.. 1998:26:185-87.27.Rasmussen SN. Haase L, Kjeldsen H, et al. Determination of renal volume by ultrasotuid scanning.J. Clin. Ultrasound., 1978:6: 160-63.

Ultrasonographic renal size in individuals without known renal disease

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Ultrasonographic renal size in individuals without known renal disease

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