Not all forms of kidney disease are exactly alike. Some kidney disease is acute, meaning it develops suddenly and is commonly reversible. Other kidney disease is considered chronic kidney disease (CKD), as it develops gradually over time and involves declining kidney function. Both acute kidney injury (AKI) and CKD affect kidney function, but they have key differences — including how they’re diagnosed and treated.

Interestingly, CKD and AKI are each risk factors for the other. If you have CKD, you’re more likely to experience AKI and vice versa. Both conditions can contribute to cardiovascular disease, and cardiovascular disease contributes to CKD. Whether you have AKI or CKD, it’s important to be aware of the impact of kidney disease on your overall health and the connections between the two conditions.

Acute Kidney Injury vs. Chronic Kidney Disease

Understanding what your kidneys do and how they work can help you better understand AKI and CKD, including their similarities and differences. Your kidneys’ main role is to filter waste and toxins out of your blood. Those waste products then leave your body in your urine. In doing this, your kidneys also balance fluids (mainly water) and electrolytes (minerals like sodium and potassium) throughout your body.

Tiny blood vessels in your kidneys called glomeruli filter your blood first, then pass it on to small tubes called renal tubules. The renal tubules remove waste and excess fluid while returning essential nutrients and necessary water to your blood. Both CKD and AKI can disrupt this process.

What Is Acute Kidney Injury?

AKI happens when your kidneys suddenly can’t filter your blood as they’re supposed to. This leads to waste products building up in your bloodstream and causes an imbalance between fluid and electrolytes. The kidney dysfunction can be mild or severe, with mild cases being more likely to be reversible.

AKI can occur when blood flow to your kidneys is blocked or slowed, often due to physical damage or injury to the kidneys. AKI is always linked to another disease or injury.

What Is Chronic Kidney Disease?

Unlike AKI, CKD involves permanent damage to your kidneys and the gradual worsening of kidney function for years. Without treatment, CKD progresses through five stages and can lead to kidney failure (which is also called end-stage kidney disease). Treatment won’t cure your CKD, but it will slow the rate of kidney damage.

There are multiple specific types of CKD that damage the kidneys in different ways, all leading to the decline of kidney function. Some of them, like immunoglobulin A nephropathy (IgAN), cause inflammation in the glomeruli that prevents them from filtering your blood properly.

Causes of Kidney Disease

AKI and CKD both have many possible causes, all of which damage the kidneys and affect how they function. Some conditions, like hypertension (high blood pressure), diabetes, and heart disease, can increase your risk of both AKI and CKD.

Acute Kidney Injury Causes

AKI starts when something physically damages your kidneys or blocks blood flow into them. AKI can also happen if the tubes connecting your kidneys to your bladder, called ureters, are blocked. Here are a few examples:

• Conditions that slow blood flow to the kidneys — Severe dehydration, severe infections, blood loss, heart attacks, certain medications
• Conditions that damage the kidneys — Blood clots in the kidneys, glomerulonephritis (inflammation of the glomeruli), toxins like alcohol or heavy metals, cholesterol deposits
• Conditions that block the ureters — Kidney stones, blood clots in the urinary tract, enlarged prostate, tumors

Chronic Kidney Disease Causes

Chronic kidney damage can be related to specific types of kidney disease or from chronic conditions that affect many parts of your body. The two most common causes of CKD are hypertension and diabetes. Here are some examples of kidney conditions that can cause chronic kidney damage:

• IgA nephropathy — IgA buildup causing inflammation in the glomeruli
• Pyelonephritis — Recurrent kidney infections
• Polycystic kidney disease — Fluid-filled cysts growing inside your kidneys
• Autoimmune diseases — Lupus, sarcoidosis, and other immune system diseases

Kidney Disease Symptoms and Diagnosis

Symptoms and when they develop can help your doctor or nephrologist determine if you have AKI or CKD. Some of the symptoms overlap, but AKI is more likely to cause symptoms from the start. However, in some cases, AKI doesn’t cause any symptoms and is diagnosed only with lab work. People with CKD don’t usually experience symptoms until later stages when kidney function is severely diminished.

Both AKI and later-stage CKD can cause symptoms that indicate poor kidney function, including:

• Edema (swelling, specifically in your hands, ankles, and feet)
• Shortness of breath
• Itchy skin
• Tiredness or low energy
• Brain fog

AKI and CKD have some different symptoms, too. For example, CKD may change your urine’s appearance. It might be foamy, bubbly, or discolored. AKI might cause you to have a low urine output, whereas CKD might cause you to pee more often than usual.

If your doctor or nephrologist believes you might have acute or CKD, they use blood tests to check your glomerular filtration rate (GFR) and levels of substances like creatinine or urea. They might also use urinalysis (a urine test) to check for proteinuria (protein in your urine) or blood in your urine. Ultrasound imaging allows your nephrologist to look at your kidneys and learn more about the damage. If the ultrasound shows your kidneys are smaller than normal, you probably have CKD.

Treating Acute vs. Chronic Kidney Disease

Getting an accurate kidney disease diagnosis is essential because acute and CKD are treated differently and have different treatment goals. With AKI, the goal is to help your kidneys heal, while the goal of CKD treatment is to slow down kidney damage and preserve as much kidney function as possible.

Acute Kidney Injury Treatment

If you have AKI, you’re most likely going to need to stay in the hospital if you’re not already there. You’ll stay until your kidneys have recovered and can do their job again.

Your healthcare team will treat the underlying cause of your AKI while also treating and preventing possible AKI complications, like hyperkalemia (high potassium in your blood). You may need dialysis for a while, which cleans your blood when your kidneys aren’t working properly. Dialysis can remove toxins and waste from your blood while your kidneys heal.

Chronic Kidney Disease Treatment

CKD treatment can involve a combination of medications and lifestyle changes to help support your kidneys. You’ll have to follow a kidney-friendly diet, and you might be prescribed ACE inhibitors or angiotensin-receptor blockers (ARBs) to manage high blood pressure, diuretics to get rid of extra fluid, or erythropoietin if you develop anemia.

Other medications may be prescribed according to the type of CKD you have. If you have IgA nephropathy, for example, you might need to take medications that calm your immune system to control the buildup of antibodies in the glomeruli. Treatments for IgA nephropathy and other CKDs may prevent you from needing dialysis or a kidney transplant, which you’ll need if your CKD progresses to kidney failure.

Acute vs. Chronic Kidney Disease Progression and Prognosis

With treatment and careful monitoring, AKI can often be reversed. Your kidneys may return to their full original function, or almost all of it. If severe AKI isn’t treated, however, it can be life-threatening.

CKD requires ongoing treatment to slow the progression of kidney damage. When CKD isn’t well controlled, it can lead to kidney failure, which means your kidneys can’t filter your blood on their own anymore. If this happens, you’ll either need a kidney transplant (a new kidney from a donor) or lifelong dialysis. Otherwise, kidney failure is life-threatening.

Talk to your doctor if you have any concerns about your kidney function, even if you feel fine. They may recommend regular testing if you’re at risk for CKD since it doesn’t typically cause symptoms in the early stages.

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On myIgANteam, people share their experiences with IgA nephropathy, get advice, and find support from others who understand.

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