|Year : 2014 | Volume
| Issue : 4 | Page : 191-197
Relationship of ultrasound renal echogenicity, serum creatinine level and CD4 cell counts in patients with human immunodeficiency virus-associated nephropathy
Philip Oluleke Ibinaiye1, Sani Suleiman Garko2, Ahidjo Ahmed3, Sa'ad Suleiman Tanimu2, Nasiru Musa Tahir2
1 Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
2 Department of Radiology, Federal Teaching Hospital, Gombe, Nigeria
3 Department of Radiology, University of Maiduguri Teaching Hospital, Maiduguri, Nigeria
|Date of Submission||22-Apr-2014|
|Date of Acceptance||11-Sep-2014|
|Date of Web Publication||14-Nov-2014|
Philip Oluleke Ibinaiye
Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna
Background: There is a paucity of information on the relationship of renal ultrasound echogenicity and serum creatinine levels to CD4 cell counts in patients with human immunodeficiency virus-associated nephropathy (HIVAN) in our local environment. This necessitated the conduct of this study. Aims and objectives: To establish a relationship between renal ultrasound echogenicity and serum creatinine levels and CD4 cell counts in adult patients with HIVAN. Settings and Design: A cross-sectional study of 100 consecutively confirmed HIV-seropositive patients aged between 19 and 65 years (mean ± standard deviation: 35 ± 10.79) comprising 32 males and 68 females with clinical and laboratory features of HIVAN was conducted at the infectious disease clinic of the University of Maiduguri Teaching Hospital, between April 2011 and September 2012. Materials and Methods: The subjects underwent renal ultrasound scan, and the degree of parenchymal echogenicity was recorded. Serum creatinine levels and CD4 lymphocyte counts were also obtained for all the patients. Statistical Analysis: The data obtained were recorded on Data sheet and analyzed using SPSS for windows version 16. Results: Of the 100 cases studied (i.e., 200 kidneys), ultrasound showed abnormal echogenicity in 192 kidneys (96%) with a grade I echogenicity in 4 patients (4%), grade II echogenicity in 36 patients (36%) and grade III echogenicity in 56 patients (56%). Four patients (4%) had a normal renal echogenicity. Majority of the patients had grade III renal echogenicity. The lower the CD4 count, the higher the degree of the renal echogenicity. Although, the higher the serum creatinine levels, the higher the degree of the renal echogenicity. Conclusion: The degree of the renal echogenicity was found to be inversely proportional to the CD4 cell counts. Prognosis also worsens with higher serum creatinine and lower CD4 cell counts.
Keywords: CD4 cell counts, human immunodeficiency virus-associated nephropathy, renal echogenicity, Serum creatinine, ultrasound
|How to cite this article:|
Ibinaiye PO, Garko SS, Ahmed A, Tanimu SS, Tahir NM. Relationship of ultrasound renal echogenicity, serum creatinine level and CD4 cell counts in patients with human immunodeficiency virus-associated nephropathy. Sub-Saharan Afr J Med 2014;1:191-7
|How to cite this URL:|
Ibinaiye PO, Garko SS, Ahmed A, Tanimu SS, Tahir NM. Relationship of ultrasound renal echogenicity, serum creatinine level and CD4 cell counts in patients with human immunodeficiency virus-associated nephropathy. Sub-Saharan Afr J Med [serial online] 2014 [cited 2019 Oct 20];1:191-7. Available from: http://www.ssajm.org/text.asp?2014/1/4/191/144733
| Introduction|| |
It was estimated in 2007 that 33.2 million people were living with human immunodeficiency virus (HIV) infection globally, 2.5 million became newly infected (1.7 million are in sub-Saharan Africa) and 2.1 million died of acquired immunodeficiency syndrome (AIDS).  An estimated 22.5 million persons living with HIV (68% of the global total) are to be found in sub-Saharan Africa.  The current prevalence rate of HIV in Nigeria is about 3.4%  and that of Borno state is 3.5%.  The prevalence of HIV in Nigeria and its resultant morbidity and mortality are, therefore, on the increase. This is attributed to low level of awareness, nonaccessibility to health care and nonavailability of highly active antiretroviral therapy to the patients. 
Human immunodeficiency virus infection has a broad spectrum of renal manifestations, and these disorders are commonly encountered in patients at all stages of HIV infection. HIV-related renal impairment can present as an acute or chronic renal disease; it can be caused directly or indirectly by HIV and/or drug-related effects that are directly nephrotoxic or lead to changes in renal function by inducing metabolic vasculopathy and renal damage. ,, The most common cause of renal failure in HIV patients is the syndrome of HIV-associated nephropathy (HIVAN), and therefore necessitates increased surveillance and adaptation of dosages of HIV drugs. ,
The striking feature of HIVAN is its predominance in black patients. ,, Most patients with HIVAN are of African descent,  presenting late in the course of their HIV-1 infection.  Once diagnosed, rapid progression to renal failure and end-stage renal disease (ESRD) necessitating dialysis, was the norm in the preantiretroviral therapy era.  Death is usually due to other HIV-related problems. ,
Because HIVAN typically occurs late in the course of HIV-1 infection, risk factors for its development include a low CD4 cell count (<200 cells/mm 3) and a high viral burden.  The biochemical feature of HIVAN is rising serum creatinine and proteinuria (>3 g/24 h). , Prognosis worsens with higher serum creatinine and lower CD4 cell counts. 
Renal ultrasound is the ideal imaging modality to demonstrate increasing renal echogenicity in HIVAN. It is affordable, noninvasive, and readily available and does not involve the use of ionizing radiation. Computerized tomography (CT) scan can also be employed for renal evaluation; however, it is expensive and delivers high radiation dose to the patient. Magnetic resonance imaging though does not involve the use of ionizing radiation and has better soft tissue definition than CT, but it is much more expensive and not readily available in our locality.
The aim of this study was to establish a relationship between renal echogenicity/serum creatinine levels and CD4 cell counts in adult patients with HIVAN.
Settings and Design
This prospective study was carried out at the University of Maiduguri Teaching Hospital, Borno state, Nigeria between April 2011 and September 2012. Borno State is located in the North-eastern part of Nigeria and has an estimated population of 4.2 million people (2006 census).  It shares boundaries with the neighboring countries of Chad, Cameroon and Niger. The inhabitants are mainly Kanuri, Babur/BURA, Shuwa, Hausa, Fulani, MANDARA and migrants from the neighboring countries.
| Materials and methods|| |
A total of 100 patients positive, for HIV antibodies as detected by enzyme-linked immunosorbent assay and confirmed by immunocomb II (Immunocombfirm) with clinical or laboratory features of HIVAN, referred from HIV dedicated clinics to Radiology Department and fulfilled the inclusion criteria were recruited for this study after obtaining an informed written consent.
Adult patients with confirmed HIV infection who may have one or the other of; Proteinuria of 2+ or >3 g of protein in 24 h urine sample, Presence of constitutional symptoms such as fatigue, malaise, anorexia and pruritus and raised serum creatinine level presenting with above features.
Patients who refused to consent, patients on immunosuppressive drug therapy, patients with hypertension, diabetes mellitus, nephrotic syndrome, widespread malignancies or on heroin and children (16 years and below).
On the enrolment into the study after satisfying the inclusion criteria, a questionnaire was administered to each patient and details regarding demographic data (age, sex, marital status and occupation), CD4 cell counts, serum creatinine level and grade of the renal echogenicity were documented.
Blood specimen for CD4 cell counts and serum creatinine level was collected and sent to the chemical pathology laboratory of the University of Maiduguri Teaching Hospital for all the patients in the study.
Renal ultrasound was carried out on all the patients who satisfied the inclusion criteria using Aloka SSD-3500 model US scanner machine with a broad band phased array transducer (3.5-15 MHz). The right kidney was examined with the patient in the supine position or turned in 45° left oblique position. The left kidney was also examined with the patient supine or in 45° right oblique position. Examination of either kidney was facilitated by requesting the patient to hold on to deep arrested inspiratory efforts. This displaced the kidney caudally, moving it away from overlying ribs. Evidence of parenchymal heterogeneity with or without echogenic striations was checked for, bilaterally and compared with parenchymal echogenicity of the liver and spleen for the right and left kidneys respectively. 
Grading of the renal echogenicity
- Grade 0: Normal; when the renal cortex is slightly less echogenic than the liver or spleen.
- Grade I: When the renal cortex is of the same echogenicity with the liver or spleen.
- Grade II: When the renal cortex is mildly to moderately more echogenic than the liver or spleen, with some loss of corticomedullary distinction.
- Grade III: When the renal cortex is severely echogenic obliterating the highly echogenic renal sinus.
The data obtained were recorded on Data sheet and analyzed using SPSS for windows version 16. The results were presented in the form of graphs, tables and charts for illustration where appropriate.
These are renal ultrasound scan echo-patterns; serum creatinine and CD4 cell counts.
Approval to carry out the study was obtained from the ethical and research committee of the University of Maiduguri Teaching Hospital. The data collected from the participants were kept with utmost confidentiality and patients had a choice to deny consent or opt out of the study at any stage.
| Results|| |
One hundred HIV-infected patients with clinical and laboratory features of HIV-nephropathy were enrolled into a prospective cross-sectional study. Sixty-eight (68%) patients were females and 32 (32%) were males. Their ages ranged between 19 and 65 years (Mean = 35 ± 10.79).
[Table 1] shows the frequency of HIVAN in the different age groups and sexes. The most prone age and sex groups occurred in females between 20 and 29 years.
Married men and women were the majority in the study representing 80%. While most of the patients in the study were either fulltime housewives or civil servants, each representing 44%.
[Figure 1] shows the distribution of the renal echogenicity. It revealed grade I echogenicity in 4 patients (4%), grade II echogenicity in 36 patients (36%) and grade III echogenicity in 56 patients (56%). Four patients (4%) had a normal renal echogenicity. Majority of the patients had grade III renal echogenicity. Homogenous echogenic parenchymal pattern (diffuse) was seen in 80% of patients while 20% had heterogeneous echogenic renal parenchymal (patchy) patterns.
|Figure 1: Frequency distribution of pattern of renal echogenicity in the patients studied|
Click here to view
The loss of corticomedullary definition (CMD) was observed in 80 patients (80%) while it was preserved in 20 patients (20%). Among the 80 patients with loss of CMD, 45 (56%) had decreased conspicuity of the renal pyramids while the pyramids were invisible in 35 (44%). Those patients with preserved CMD had either normal or slightly prominent pyramids.
[Table 2] shows the serum creatinine level of the patients studied. The minimum and maximum serum creatinine levels were 24 mmol/l and 1048 mmol/l respectively while the average serum creatinine level was 399 mmol/l (~4.0 mg/dl).
|Table 2: The frequency distribution and percentage of the serum creatinine level of the patients studied|
Click here to view
[Table 3] is the summary of the CD4 counts of the patients studied. Most of the patients (96%) had a CD4 count of less than 200 while only 4 patients (4%) had a CD4 of >200. The range of CD4 counts was between 42 and 252.
|Table 3: The frequency distribution and percentage of the CD4 count of patients studied|
Click here to view
[Table 4] shows the relationship between renal cortical echogenicity and serum creatinine level. There was a statistical significant correlation between the serum creatinine and the degree of the renal echogenicity (r = 0.9). Patients with grade III renal cortical echogenicity (56%) had much higher values of raised creatinine levels (348-1048 mmol/l) as compared to the lower value of raised creatinine (245 mmol/l) in those patients with grade I renal cortical echogenicity (4%). The higher the raised serum creatinine level, the greater the degree of the renal echogenicity.
|Table 4: Correlation of patients' serum creatinine with renal echogenicity|
Click here to view
[Table 5] shows the relationship between renal cortical echogenicity and CD4 counts. There was significant negative correlation between the degree of renal echogenicity and CD4 count (r = −0.8). Those patients with CD4 count above 200 showed lower grade (grade I) of renal cortical echogenicity while most of the patients with CD4 count below 200 (60%) had grade III renal cortical echogenicity. The lower the CD4 count, the higher the degree of the renal echogenicity.
[Figure 2], [Figure 3], [Figure 4], [Figure 5] are ultrasound images depicting the various grades of renal parenchymal echogenicity of patients studied.
|Figure 2: A 30-year-old man with HIV nephropathy. Longitudinal sonogram of the right kidney reveals grade III diffuse increase in cortical echogenicity. There is loss of central sinus echogenicity. Note the shrunken kidney depicting end stage diseases|
Click here to view
|Figure 3: Longitudinal sonogram of the right kidney showing grade I renal echogenicity in a patient with HIV-associated nephropathy. Note; renal echogenicity is same with that of liver parenchyma|
Click here to view
|Figure 4: Longitudinal sonogram of the right kidney showing grade II renal echogenicity in a patient with HIV-associated nephropathy. Note loss of corticomedullary defi nition but central sinus echogenicity is preserved|
Click here to view
|Figure 5: Longitudinal sonogram of the right kidney showing grade III renal echogenicity in a patient with HIV-associated nephropathy. Note loss of central sinus echogenicity|
Click here to view
| Discussion|| |
The age distribution of HIVAN patients as reported by other workers is 20-64 years ,, which is similar to the age range in this study. It shows the fact that HIVAN is more common in people in their reproductive and sexually active age, as seen in the previous reports. ,,
The fact that patients involved in this study were predominantly black Africans who presented late in the course of their HIV-1 infection is in keeping with the studies by Freedman et al.,  Mockrzycki et al. and Bourgoignie et al.  Schoenfeld et al. reported that there is a high incidence of HIVAN and its resultant ESRD in patients of African descent, and this is attributed to a genetic predisposition to the disease. This association is supported by the work of other researchers. ,,
The male:female ratio reported by authors in other parts of the world , and Nigeria  found a male preponderance, while Mockrzycki et al. found an even sex distribution. However, more females are involved in this study possibly due to polygamy, and the women may be presenting to the hospital more than the men.
Married men and women were the majority of the patients in the study. This may be due to the socio-cultural and religious factors leading to early marriage rather than the low level of education and lack of awareness.
Majority of the patients were fulltime housewives who were unemployed and therefore belong to low socioeconomic stratum of the society. The remaining were civil servants, students and businessmen and women. This low socioeconomic status coupled with poverty, ignorance and disease further promote the spread of HIV and subsequent development of HIVAN in these patients.
N'zi et al.,  did an abdominal ultrasound on 146 grade IV AIDS patients in Cote d'Ivoire and detected hyper-echoic kidneys suggestive of HIVAN in 13.7%. Obajimi et al.,  in 2008 conducted abdominal ultrasound on 391 HIV/AIDS patients in Ibadan, and demonstrated increased renal cortical/medullary echo-texture in 8.4% of that series. While the increase in the renal echogenicity is in conformity with our study, a high percentage in our study is presumably because renal USS was carried out on patients with features of HIVAN most of whom had presented late in the course of the disease.
In a study by Hamper et al.,  a standard grading system was employed to evaluate the sonographic renal cortical echogenicity. The degree of increasing echogenicity was found to be directly proportional to the severity of the disease, and this is in agreement with this study. They postulated that the main factors for the increased echogenicity in AIDS nephropathy are the striking tubular abnormalities seen in these patients.
Majority of the previous researchers ,,, found that most patients with HIVAN have advanced renal failure at the time of diagnosis with the serum creatinine level usually high. Emem et al. studied 400 HIV/AIDS patients in Ife using biochemical parameters (proteinuria and serum creatinine) and found elevation of serum creatinine in 38% of the patients. This is not in any way different from the work of Atta et al. who described serum creatinine level of 300 mmol/l or more in patients with HIVAN. These authors further explained that creatinine levels quantify the ability of the kidneys to clear the blood of waste products. As kidney function declines (for instance in HIVAN), creatinine is less effectively cleared from the blood hence the level rises. This study is in conformity with that of the above workers. However, Burns et al. reported a cohort of patients with HIVAN and mild renal insufficiency with normal creatinine level (mean serum creatinine of 114.9 mmol/l). This was not observed among our patients.
This study found a statistically significant correlation between the degree of increased renal echogenicity and the raised serum creatinine level (direct exponential relationship). It also found out that diffuse renal parenchymal echo-patterns were associated with the values of elevated serum creatinine, whereas patchy parenchymal echo-patterns were seen with lower values of elevated serum creatinine. A series of studies ,,,,, even though did not directly correlate serum creatinine levels to the renal echogenicity, but many of them showed that there is a rapid rise in creatinine levels among patients with HIVAN, resulting in renal failure.
Di Fiori et al.  and Szczech et al.  concluded that a significantly higher serum creatinine levels among the patients with HIVAN compared with HIV-positive patients without HIVAN is said to play a role in the increased renal echogenicity and the diffuse renal echo-pattern observed in these patients. HIVAN seem to produce increased echogenicity along with steep increases in creatinine levels. Atta et al. further described that renal failure develops so quickly that most of the patients with HIVAN present with renal failure, even after being seen several months earlier with normal creatinine levels.
Winston et al.  in 1999 and Szczech et al.  in 2002 reported that HIVAN typically occurs late in the course of HIV-1 infection, and the risk factors for its development include a low CD4 cell count (<200 cells/mm 3) and a high viral burden. Prognosis worsens with low CD4 count. The outcome of our study is in support of the above findings.
A series of studies ,,,, found that the degree of the renal echogenicity varies with the degree of immunosuppression (using CD4 T-lymphocyte count of <200 cells/mm 3 as a marker of significant immunosuppression). This implies that the degree of renal cortical echogenicity is inversely proportional to the CD4 count. Patients with CD4 lymphocyte count above 200 cells/mm 3 commonly have a lesser degree of the renal echogenicity. This study also found a statistically significant negative correlation between CD4 count and the renal echogenicity (r = -0.8).
The data in this report support the idea that HIVAN exists as a separate entity as opposed to the controversy that existed in the earlier report by Rao et al.,  as to whether HIVAN is an actual disease entity or simply a misdiagnosed heroin nephropathy. No subject in this study had a history of heroin use. Focal segmental glomerulosclerosis is a histologic feature seen in both HIVAN and heroin-associated nephropathy.
| Conclusion|| |
The degree of the renal echogenicity was found to be inversely proportional to the CD4 cell counts, but showed positive linear correlation with increasing serum creatinine level. Prognosis worsens with higher serum creatinine and lower CD4 cell counts.
| Recommendation|| |
Monitoring increasing levels of raised serum creatinine and falling levels of low CD4 counts should be used to project the degree of the renal echogenicity that prognosticates on the progression to renal failure in patients with HIVAN.
| References|| |
UNAID/WHO2007AIDSEpidemicUpdate. Available from: http://www.who.int/mediacentre/news/releases/2007/pr61/en/index.html. [Last accessed on 2008 Aug 08].
NARHS Plus 2012. Available from: https//www.twiter.com/SFHNigeria/status/408659719176196096.
FMOH. HIV seroprevalence and sentinel survey 2005. National AIDS/STDs Control Programme. Abuja: Federal Ministry of Health; 2005.
Röling J, Schmid H, Fischereder M, Draenert R, Goebel FD. HIV-associated renal diseases and highly active antiretroviral therapy-induced nephropathy. Clin Infect Dis 2006;42:1488-95.
D'Agati V, Appel GB. Renal pathology of human immunodeficiency virus infection. Semin Nephrol 1998;18:406-21.
Rao TK, Friedman EA. Outcome of severe acute renal failure in patients with acquired immunodeficiency syndrome. Am J Kidney Dis 1995;25:390-8.
Klotman PE. HIV-associated nephropathy. Kidney Int 1999;56:1161-76.
Winston JA, Klotman ME, Klotman PE. HIV-associated nephropathy is a late, not early, manifestation of HIV-1 infection. Kidney Int 1999;55:1036-40.
Freedman BI, Soucie JM, Stone SM, Pegram S. Familial clustering of end-stage renal disease in blacks with HIV-associated nephropathy. Am J Kidney Dis 1999;34:254-8.
Mokrzycki MH, Oo TN, Patel K, Chang CJ. Human immunodeficiency virus-associated nephropathy in the Bronx: Low prevalence in a predominantly Hispanic population. Am J Nephrol 1998;18:508-12.
Bourgoignie JJ, Ortiz-Interian C, Green DF, Roth D. Race, a cofactor in HIV-1-associated nephropathy. Transplant Proc 1989;21:3899-901.
Di Fiori JL, Rodrigue D, Kaptein EM, Ralls PW. Diagnostic sonography of HIV-associated nephropathy: New observations and clinical correlation. AJR Am J Roentgenol 1998;171:713-6.
Szczech LA, Gange SJ, van der Horst C, Bartlett JA, Young M, Cohen MH, et al.
Predictors of proteinuria and renal failure among women with HIV infection. Kidney Int 2002;61:195-202.
National Population Commission: National Population Census, Nigeria. Nigerian Population State by State Analysis, National Population Commission; 2006.
Atta MG, Longenecker JC, Fine DM, Nagajothi N, Grover DS, Wu J, et al.
Sonography as a predictor of human immunodeficiency virus-associated nephropathy. J Ultrasound Med 2004;23:603-10.
Rao TK, Friedman EA, Nicastri AD. The types of renal disease in the acquired immunodeficiency syndrome. N Engl J Med 1987;316:1062-8.
N'Zi PK, Coulibaly A, N'Dri K, Ouattara ND, Diabate SA, Zunon-Kipre E, et al.
[Ultrasound aspects of abdominal involvement in adults with HIV infections in the Ivory Coast: Apropos of 146 cases]. Sante 1999;9:85-8.
Saidu SA, Makusidi MA, Isyaku K, Maaji SM. Abdominal ultrasound findings in AIDS patients in Sokoto: A preliminary report. Borno Med J 2005;2:11-3.
Obajimi MO, Atalabi MO, Ogbole GI, Adeniji-Sofoluwe AT, Agunloye AM, Adekanmi AJ, et al.
Abdominal ultrasonography in HIV/AIDS patients in southwestern Nigeria. BMC Med Imaging 2008;8:5.
Hamper UM, Goldblum LE, Hutchins GM, Sheth S, Dahnert WF, Bartlett JG, et al.
Renal involvement in AIDS: Sonographic-pathologic correlation. AJR Am J Roentgenol 1988;150:1321-5.
Rao TK, Filippone EJ, Nicastri AD, Landesman SH, Frank E, Chen CK, et al.
Associated focal and segmental glomerulosclerosis in the acquired immunodeficiency syndrome. N Engl J Med 1984;310:669-73.
Emem CP, Arogundade F, Sanusi A, Adelusola K, Wokoma F, Akinsola A. Renal disease in HIV-seropositive patients in Nigeria: An assessment of prevalence, clinical features and risk factors. Nephrol Dial Transplant 2008;23:741-6.
Burns GC, Paul SK, Toth IR, Sivak SL. Effect of angiotensin-converting enzyme inhibition in HIV-associated nephropathy. J Am Soc Nephrol 1997;8:1140-6.
Wachsberg RH, Obolevich AT, Lasker N. Pelvocalyceal thickening in HIV-associated nephropathy. Abdom Imaging 1995;20:371-5.
Ross MJ, Klotman PE. HIV-associated nephropathy. AIDS 2004;18:1089-99.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
|This article has been cited by|
||Renal Echogenicity as a Predictor of Human Immunodeficiency Virus–Associated Nephropathy: A Cross-Sectional Study at a Tertiary Hospital in Lagos, Southwest Nigeria
| ||Cletus Uche Eze,Charles Ugwoke Eze,Adekunle A. O. Adeyomoye |
| ||Journal of Diagnostic Medical Sonography. 2018; 34(4): 261 |
|[Pubmed] | [DOI]|
||A cross-sectional study on renal involvement among HIV-infected patients attending a tertiary care hospital in Kolkata
| ||Soumyadip Chatterji,Sudeshna Mallik,Dipak Pal,Dushyant Lahre,Sayan Chakraborty,Manab Kumar Ghosh,Arindam Naskar,Rajendra Pandey,Bibhuti Saha |
| ||Transactions of The Royal Society of Tropical Medicine and Hygiene. 2018; 112(6): 294 |
|[Pubmed] | [DOI]|
||Sonographic evaluation of kidney echogenicity and morphology among HIV sero-positive adults at Lagos University Teaching Hospital
| ||Cletus Uche Eze,Charles Ugwoke Eze,Adekunle Adeyomoye |
| ||Journal of Ultrasound. 2018; |
|[Pubmed] | [DOI]|
||SONOGRAPHIC GRADING OF RENAL CORTICAL ECHOGENICITY AND RAISED SERUM CREATININE IN PATIENTS WITH CHRONIC KIDNEY DISEASE
| ||Arvinder Singh,Kamlesh Gupta,Ramesh Chander,Mayur Vira |
| ||Journal of Evolution of Medical and Dental Sciences. 2016; 5(38): 2279 |
|[Pubmed] | [DOI]|