When symptoms appear, doctors often arrive too late
En España, uno de cada siete adultos convive con una enfermedad renal crónica que avanza en silencio, sin síntomas, hasta que el daño ya es profundo. Los especialistas en nefrología señalan que esta invisibilidad no es inevitable: análisis de sangre y orina, sencillos y asequibles, pueden revelar el deterioro renal y el riesgo cardiovascular antes de que el cuerpo emita señal alguna. La propuesta es tan modesta como urgente —una revisión anual a partir de los 40 años— y sin embargo podría cambiar el destino de millones de personas que hoy desconocen que sus riñones están fallando.
- El 14% de los adultos españoles tiene enfermedad renal crónica, pero la mayoría lo ignora porque la enfermedad no duele, no avisa y no se ve hasta que el daño es severo.
- Cuando aparecen los síntomas —fatiga persistente, piernas hinchadas, anemia que no cede— los médicos suelen llegar demasiado tarde para revertir el deterioro.
- El peligro más letal no es el fallo renal en sí, sino las complicaciones cardiovasculares que lo acompañan: los riñones dañados arrastran al corazón, las arterias y el metabolismo.
- Dos pruebas básicas —el filtrado glomerular en sangre y el cociente albúmina-creatinina en orina— pueden detectar el daño antes de que el paciente sienta nada, y su coste es mínimo.
- Los nefrólogos presionan para que el cribado anual desde los 40 años se convierta en práctica estándar, pero la pregunta abierta es si el sistema sanitario lo adoptará antes de que más personas lleguen demasiado tarde.
Uno de cada siete adultos en España tiene enfermedad renal crónica sin saberlo. La enfermedad avanza durante años sin dejar rastro visible, y cuando por fin se manifiesta —con cansancio extremo, edemas o anemia— el daño renal suele estar ya muy avanzado. Este silencio es precisamente lo que ha llevado a los especialistas a reclamar un cambio en la forma de hacer prevención: análisis de sangre y orina una vez al año a partir de los 40.
La Organización Mundial de la Salud ha identificado la enfermedad renal crónica como una crisis de salud pública en crecimiento, y los datos españoles lo confirman. La mayoría de quienes la padecen no han recibido diagnóstico alguno. La Dra. Belén Alemany, nefróloga especializada en riesgo cardiovascular y enfermedad cardiorrenal en el Hospital Vithas Valencia 9 de Octubre, lo resume con claridad: cuando aparecen los síntomas, los médicos frecuentemente llegan tarde. Y lo que hace esta situación especialmente grave es que la enfermedad renal no mata principalmente por fallo renal, sino por las complicaciones cardiovasculares que la acompañan. Los riñones están profundamente conectados con el corazón, las arterias y el metabolismo; el daño en uno repercute en todos.
Los factores de riesgo —hipertensión, diabetes, obesidad, colesterol elevado, tabaquismo, envejecimiento vascular— se concentran y aceleran precisamente a partir de los 40 años, lo que refuerza la lógica del cribado temprano. Las dos mediciones clave son el filtrado glomerular estimado, que indica cómo filtran los riñones los residuos del organismo, y el cociente albúmina-creatinina en orina, que puede revelar daño estructural en el sistema de filtración renal y actuar como señal de alerta temprana de enfermedad cardiovascular.
Lo que hace esta propuesta especialmente poderosa es su sencillez: una extracción de sangre y una muestra de orina tienen un coste muy bajo y un potencial preventivo enorme. Una sola prueba podría cambiar el rumbo de un paciente, detectando la enfermedad en un momento en que la intervención todavía es eficaz. La pregunta que queda abierta es si España convertirá este cribado en práctica habitual, o si millones de personas seguirán viviendo sin saber que sus riñones están fallando en silencio.
One in seven Spanish adults is living with chronic kidney disease without knowing it. The condition creeps forward silently, often for years, leaving no trace of itself until the damage has already taken root. By the time a person feels the weight of it—the exhaustion, the swelling in the legs, the anemia that won't lift—the kidneys have usually deteriorated far beyond what early intervention could have prevented. This is the central problem that has prompted kidney specialists across Spain to push for a simple change in how we approach health screening: annual blood and urine tests starting at age 40.
The World Health Organization has recently flagged chronic kidney disease as a growing public health crisis globally, and Spain's numbers bear that out. Roughly one in seven adults here carries the diagnosis, yet the vast majority remain unaware. The disease's invisibility is its defining feature. It advances without fanfare, without the warning signs that might send someone to a doctor's office. By the time symptoms emerge, the organ damage is often already severe.
Dr. Belén Alemany, a nephrologist at Hospital Vithas Valencia 9 de Octubre who specializes in cardiovascular risk and cardiorenal disease, frames the problem plainly: only a small fraction of patients know they have kidney disease. When symptoms finally appear—fatigue, swelling, anemia—doctors frequently arrive too late. The damage is already entrenched. What makes this particularly urgent is that kidney disease doesn't typically kill through kidney failure alone. The real threat lies in the cardiovascular complications that shadow it. The kidneys are woven into the body's larger systems: the heart, the arteries, metabolism, vascular inflammation. Damage to one reverberates through all of them.
The risk factors for chronic kidney disease cluster around conditions that become more common as people age. High blood pressure, diabetes, obesity, elevated cholesterol, smoking, and vascular aging all increase vulnerability—and all of these conditions tend to accelerate after age 40. This is why specialists are advocating for early screening strategies using tests that are both simple and inexpensive. A basic blood draw and urine sample can reveal an enormous amount about a person's kidney and cardiovascular health.
Two measurements form the foundation of early detection. The first is estimated glomerular filtration rate, derived from blood creatinine levels, which shows how well the kidneys are filtering waste. The second is the albumin-to-creatinine ratio in urine, which can reveal structural damage in the kidney's filtration system. This second marker has become increasingly important because of what it signals about the heart and blood vessels. The presence of albumin in urine acts as an early warning system for vascular damage. It can alert doctors to kidney disease, heart failure, or cardiovascular disease before a patient experiences any symptoms at all.
What makes this approach so compelling is its accessibility. These are not expensive, complicated tests. A basic blood and urine panel costs very little and has enormous potential to change outcomes. Alemany emphasizes the point: these studies are extremely affordable, and their preventive impact could be transformative. A single screening could fundamentally alter a patient's trajectory, catching disease at a stage where intervention still matters. The question now is whether Spain's health system will make annual screening from age 40 standard practice, or whether millions of people will continue moving through their lives unaware that their kidneys are failing.
Notable Quotes
Only a small part of patients know they have kidney disease. When symptoms like fatigue, swelling, or anemia appear, we often arrive too late and the kidney damage is already advanced.— Dr. Belén Alemany, nephrologist at Hospital Vithas Valencia 9 de Octubre
The kidney patient usually doesn't die from the kidney itself, but from cardiovascular complications. The kidney is deeply connected to the heart, arteries, metabolism, and vascular inflammation.— Dr. Belén Alemany
The Hearth Conversation Another angle on the story
Why does kidney disease stay hidden for so long?
The kidneys are remarkably resilient. You can lose a lot of function before your body sends up distress signals. By the time you feel tired or notice swelling, you've often already lost significant capacity. It's like a bridge losing structural integrity—the collapse doesn't happen until the damage is already catastrophic.
So the real danger isn't kidney failure itself?
Exactly. Most people with kidney disease don't die from kidney failure. They die from heart attacks and strokes. The kidneys regulate blood pressure, electrolytes, inflammation. When they fail, everything connected to them fails too.
And these tests—they're really that simple?
Blood and urine. That's it. You get two numbers: how well your kidneys filter, and whether protein is leaking into your urine. The second one is almost like a canary in the coal mine for your whole cardiovascular system.
Why hasn't this screening become standard already?
Partly inertia. Partly the fact that kidney disease was seen as a specialist problem, not a public health issue. But the numbers have changed. One in seven people. That's not a niche problem anymore.
What changes if someone gets screened at 40 and finds out they have it?
Everything. You can slow it down with medication, diet, blood pressure control. You can prevent the cardiovascular complications. You might never need dialysis. Without screening, you're just waiting for the crisis.