ULTRASONOGRAPHIC MEASUREMENT OF RENAL DIMENSIONS: IT’S CORRELATION WITH BODY SURFACE AREA IN ADULTS

Address for Correspondence: Dr. Turlika Sinha, Associate professor of Anatomy, Silchar Medical College, P.O.: Ghungoor, Silchar-14, Cachar, Assam, PIN: 788014, India. Mobile No: (+91)9435043209 E-Mail: dr.turlikasinha@rediffmail.com Introduction: Ultrasound is the first imaging modality used to assess the kidneys and renal tract due to its easy accessibility, lack of radiation and low cost. The size of kidney is considered an important indicator for various clinical signs. Ultra-sonographic measurement of renal dimensions such as length, breadth and thickness are important parameters in diagnosis and management of kidney diseases as there is a close proximity between renal size and its function. Aim: The aim of the present study was to ascertain the renal dimensions in adult by ultrasonography and to correlate with somatic parameters like age, sex, height and body surface area. Methods: This study was carried out on 118 patients (51 male & 67 female) taking measurements of 236 kidneys having no radiologic evidence of renal diseases. Renal dimensions of right were compared with the left. The volume of the kidney was correlated with age, sex, height and body surface area. Results: The present study revealed that the volume of left kidney was more than the right in both male and female. The size of kidney in male was larger than female. The volume of kidney showed linear relationship with the body surface area both in male and female. However, volume of kidneys decreased from sixty years of age. Conclusion: Measurements of renal dimensions can be obtained quickly and easily with ultrasonography having advantage of not exposing the patients to ionizing radiation. This allowed us to find differences in relation to age, sex, weight and height. There is a gender difference in adult kidney sizes. The renal length is correlated best with height and body surface area.


INTRODUCTION
International Journal of Anatomy and Research, Int J Anat Res 2018, Vol 6(4. indicator for various clinical signs as it gets affected by congenital anomalies, neoplasm, diabetes mellitus and hypertension. The deviation of renal parameters from established normal values is an important criterion in Ultrasound is the first imaging modality used to assess the kidneys and renal tract due to its easy accessibility, lack of radiation and low cost [1]. The size of kidney is considered an important diagnosing kidney disease [2]. Ultrasonography is a valuable non-invasive technique to assess renal size and to investigate patients who are suspected of having kidney diseases. It is often the only method required for renal imaging and has the advantage of showing other abdominal, pelvic and retroperitoneal pathology [3]. Ultra-sonographic measurement of renal dimensions such as length, breadth and thickness are important parameter in diagnosis and management of kidney diseases as there is a close relationship between renal size and its function [4]. Renal length as measured by ultrasonography is a simple, practical and reproducible measurement and widely accepted to monitor renal size [5]. The size of the kidney and its dimensions are influenced by age, gender, height and weight of the individuals. It is also well known that the right kidney is smaller in size than the left kidney independent of gender. While data on normal ranges for renal dimensions are available from Western literature, little data are available from the Indian subcontinent. A renal size of 9 cm, widely accepted as the cut-off to indicate irreversible renal disease in most populations, is a size often seen in normal and healthy Indian adults [6]. In common practice, measurements of renal dimensions are compared with the measurements that are predicted by standard nomograms. Since our currently used renal nomogram in India is based on the western database, it may lead to false positive and false negative diagnosis of kidney condition. A normal functioning kidney usually have renal volume specific to particular gender and ethnicity. The ultra-sonographic measurement of renal dimensions is very important to determine the health of the individuals and also to detect any abnormalities present in the kidneys [4]. Therefore, the current research is conducted as a first step to formulate a nomogram to provide a better accuracy of measurements of renal dimensions in terms of making a proper medical diagnosis and also during monitoring the disease progress for the adult population in North-East India. AIM: The aim of the present study was to ascertain the renal dimensions in normal adult by ultrasonography. Our main objective was to correlate dimensions of kidneys with somatic parameters like age, sex, height and body surface area. This study was carried out on 236 kidneys of 118 patients in the Department of Anatomy and Radiology of Silchar Medical College & Hospital after approval by Institutional Ethical committee. Informed consent was taken from all participants. The cases (51 male & 67 female) were selected on the basis of having no radiologic evidence of renal diseases. Patients with known history of kidney diseases including renal stone or with prior abdominal surgery for renal causes were excluded from the present study. The cases were categorized into five age groups (Table-1  The patients' height and weight were measured before the ultrasound examination. Height was measured without footwear, using a stadiometer. Body surface area (BSA) was calculated by breadth and thickness of both the kidneys were measured in centimeters. Mean with standard deviations of length, breadth and thickness were calculated. The volume of the kidney was calculated by using the formula:

DISCUSSION
in renal length after age of 70 by Saeed Z [17]. The right kidney usually is smaller than the left by Gheissari A [18]. Karim et al [19] reported that the left kidney size was found to be larger as compared to the right and the size increased with age till the 5th decade of life. The male renal size was found to be greater than the female renal size with the same age group. Fernandes M M R et al [20] showed a reduction of renal size for individuals in the 7th decade life compared to the 3rd and 4th decades. Murlimanju B V [21] reported that the volume of right kidney was significantly smaller than that of the left. Raza et al [22] observed that left kidney was significantly larger than right in length, width, parenchymal thickness and volumes. Left kidney was significantly larger than right and larger renal sizes were seen bilaterally in males compared to females. The present study also revealed similar findings that the left kidney size was larger than right. Kidney volume was found to be significantly greater in males than females amongst the study population and the correlation of renal volume with age & body weight of an individual was found to be significant by Talhar et al [23]. According to Rathore et al [24], the volume of both the right and the left kidneys was higher among males compared with females. However, there was no statistically significant difference between volumes of the right and left kidneys in either sex. The volume of left kidney was more than the right in both male & female in the present study and the volume of kidneys showed linear relationship with the body surface area and height (chart 3 & chart 4).
Gebrehiwot M et al [7] found that the left kidney was longer than the right and the mean kidney length was greater in men than in women. Okoye I J et al [8] and El-Reshaid W [9] reported the mean renal length of males were slightly higher than those of females. Kolade-Yunusa [10] observed the renal dimensions among the subjects were higher on the left side than the right. Discrepancy between right and left renal length of up to 1.5 cm was considered to be within normal limits by Butler P [1]. Present study also revealed similar findings having left kidney length more than right kidney both in male and female. Renal length in our study was quite similar to those obtained by Sahni D [11] in north India. However, Barton EN et al [12] reported no difference in width between right or left kidneys in the group as a whole or within either gender.
Muthusami P et al [6] in his study showed no significant right-left difference in length or width with a significant decline in bilateral renal length after the age of sixty years. Glodny B et al [13] found that the kidney length increased significantly and breadth slightly upto 5 th decade of life and the size decreased in both gender thereafter. There was linear correlation between height and length & width of kidney. The present study also showed significant correlation between length of kidney and body height. Prasad and Kumar [14] confirmed that the age was a factor influencing the length of the kidney and the mean renal length of both kidneys found to increase with advancing age upto 60 years. The present study also showed decrease in renal length and size from sixty years of age. Egberongbe et al [15] showed that the renal volume was higher in the left than the right kidney in both sexes and volume of kidneys decreased with age. The volume of kidney decreased after 60 years of age in the present study. According to Emamian et al [16], renal size decreased with age, almost entirely because of parenchymal reduction. Renal volume correlated best with total body area and the length correlated best with body height. Males had larger kidney sizes than females, age however was only associated with a decrease

CONCLUSION
Measurements of renal dimensions can be obtained quickly and easily with ultrasonography. This allowed us to find differences in renal dimensions on the basis of age, sex, weight and height. Ultrasonography has advantages in measuring renal dimensions as the patients are not exposed to ionizing radiation. There is a gender difference in adult kidney sizes. The renal length is correlated best with body height and body surface area. Variations in measurements of renal dimensions have gained much research attention as they are believed to possess significant clinical importance. The present study signifies the potential of ultrasound as a useful tool for diagnostic and follow-up purposes of kidney and its associated diseases. By extending the present research and including data from other parts of the country, we can formulate age, sex and height specific nomogram for kidney dimensions for adequate comparison in evaluation of kidney.