A study by researchers at AIIMS has found that among people with obesity and an unhealthy metabolic profile, a significant proportion also have excess fat accumulation around the kidneys — a finding that could be associated with an increased risk of kidney and cardiovascular complications.More significantly, the study highlights that certain biomarkers detectable in blood or urine may identify early kidney injury before it is detectable through conventional kidney-function tests or imaging.The findings are part of ongoing ICMR-supported research involving 44 obese patients admitted to AIIMS. Researchers found that 77 percent of those classified as metabolically unhealthy had excess renal sinus fat, compared with 55 percent of those who were metabolically healthy. Metabolic health is assessed through measures such as blood sugar and blood pressure.“Patients with poorer metabolic health were found to have substantially higher levels of fat around the kidneys,” said Dr Amandeep Singh, an assistant professor of medicine at AIIMS Delhi and the study’s lead researcher.The researchers said these findings show that metabolic health may matter as much as, or perhaps more than, body weight alone when it comes to the accumulation of fat around the kidneys.“Kidney fat was lowest in metabolically healthy non-obese participants,” saidDr Singh. “How obese you are may matter less than how metabolically unwell you are. Two patients can have the same BMI, but the one with abnormal blood sugar or blood pressure may carry far more fat around the kidney than the one without.”Story continues below this adDr Singh said the kidney’s response to fat accumulation unfolds gradually. In the early stages, as fat builds up around the kidney, the glomerular filtration rate – a measure of how much blood the kidneys filter each minute – may actually increase.Over time, he said, this process can progress to an “obese kidney,” potentially marking a more advanced stage of kidney stress.NGAL could offer an early warning signal The challenge, researchers said, is that conventional blood tests may not reveal this damage until kidney function has already begun to deteriorate.Story continues below this adDr N K Vikram, professor of medicine at AIIMS and a co-investigator in the study, said standard measures of kidney function can underestimate the extent of kidney impairment in people who are overweight or obese. “Conventional blood tests often fail to accurately reflect true renal function in individuals living with overweight or obesity,” he said.This is where newer biomarkers such as serum NGAL may have a role. NGAL, a protein associated with kidney injury and inflammation, was substantially higher among adults with greater degrees of obesity in the study.The finding raises the possibility that NGAL could identify obesity-related kidney stress at an earlier stage.But the researchers caution that the biomarker is not yet ready for routine screening. “These findings suggest that NGAL could help identify obesity-related renal stress earlier, but larger longitudinal studies are needed before it can be recommended as a routine screening test,” Dr Vikram said.Story continues below this adDr Singh said another peer-reviewed study by his team at AIIMS, which looked at obese adults who did not have diabetes, found a similar link between higher BMI and higher levels of NGAL. This suggests that obesity itself may put stress on the kidneys, even in people who do not have diabetes or other metabolic problems. “At the same time, metabolic problems such as high blood sugar and blood pressure may add to that damage,” Dr Singh said.The close link between obesity and metabolic problems was also seen in the current study. About 30 to 40 percent of the patients had both obesity and Type 2 diabetes with insulin resistance.Dr Singh said that as body weight increases, the amount of fat and tissue around the kidneys may also increase.This, he said, means doctors may need to look beyond a patient’s weight or BMI and also consider how healthy their metabolism is.Story continues below this ad“We need to start asking not just how obese a patient is, but how metabolically unwell they are,” he said. “That may matter more for the kidney.”