Swollen Legs Or Ankles? These Tests Could Reveal Why

If you've noticed your legs, ankles, or feet looking puffy or feeling unusually heavy, you're experiencing what's commonly known as oedema. This swelling can range from a mild inconvenience at the end of a long day to a persistent and concerning symptom. For many, especially seniors and sedentary workers, whose circulation might be less active, this fluid retention is a common complaint that can impact comfort, mobility, and overall well-being.

While minor swelling can often be attributed to standing for too long, heat, or simple gravity, persistent or significant leg and ankle swelling could be your body's way of signalling a more serious underlying health issue. Ignoring it or simply elevating your legs might offer temporary relief, but it won't address the root cause of vital organs like your kidneys or heart are involved. Fortunately, specific blood tests can offer crucial insights, helping your doctor understand what might be causing your swelling and guiding you towards an accurate diagnosis and an effective solution for lasting relief. This guide will explore the various blood tests that can help identify the triggers behind your constant leg or ankle swelling.

What Causes Swelling in the Lower Limbs?

Swelling in the legs and ankles, medically known as peripheral oedema, occurs when excess fluid accumulates in the tissues. Under normal conditions, fluid moves between your blood vessels and surrounding tissues in a carefully controlled balance. When this balance is disrupted, fluid can leak out of the vessels and pool in the lower limbs, leading to visible puffiness or heaviness.

Common reasons for mild, temporary swelling include:

• Prolonged standing or sitting: Staying in the same position for extended periods reduces circulation and causes fluid to pool in the lower limbs due to gravity.
• Warm weather: Heat causes blood vessels to expand, which can lead to increased fluid leakage into surrounding tissues.
• High salt intake: Excess dietary sodium leads to water retention in the body, contributing to swelling.
• Medications: Certain drugs, including blood pressure medications, anti-inflammatory agents, and hormone therapies, can cause the body to retain fluid.
• Pregnancy: Hormonal changes and pressure from the growing uterus can reduce blood return from the legs, resulting in leg and ankle swelling.

While these common causes are often manageable with lifestyle adjustments, when swelling becomes constant, severe, or accompanied by other symptoms, it's crucial to investigate further. In such cases, blood tests can provide critical insights into internal imbalances that might be contributing to the problem.

When to Consider Blood Tests for Swollen Legs or Ankles?

If your leg or ankle swelling is more than just a temporary issue, especially if it affects your daily life or comes with other symptoms, it's time to talk to your doctor about blood tests. Consider these tests if you experience:

• Persistent Swelling: If the swelling in your legs or ankles occurs daily for weeks or months, doesn't improve overnight, or is worsening over time.
• Swelling in Only One Leg: While bilateral swelling is common, swelling primarily in one leg could indicate a more localised issue, such as a blood clot.
• Accompanied by Other Symptoms: If you also notice:
  Shortness of breath, especially when lying down or with exertion.
  Chest pain or heart palpitations.
  Fatigue, weakness, or changes in urination frequency.
  Sudden weight gain.
  Skin changes over the swollen area, such as tightness, shininess, or discolouration.
  Abdominal swelling.
• Impact on Daily Life: If the swelling is causing significant discomfort, making it difficult to walk, stand, or wear shoes (especially relevant for seniors and sedentary workers).

Key Blood Tests to Help Identify the Cause of Leg and Ankle Swelling

Persistent swelling in your legs or ankles may be more than a temporary reaction to standing or heat. It can signal underlying conditions affecting your kidneys, heart, liver, or nutritional status. Blood tests play a vital role in identifying these causes and guiding appropriate treatment.

1. Kidney Function Tests (Creatinine, BUN, eGFR)

What they measure: These tests assess how efficiently your kidneys are filtering waste and excess fluids from the blood.

• Creatinine and Blood Urea Nitrogen (BUN) are waste products that build up when the kidneys aren’t working properly.
• Estimated Glomerular Filtration Rate (eGFR) is a calculation based on creatinine, age, sex, and other factors. It gives a reliable estimate of overall kidney function.

Why they’re important: When kidney function declines, the body retains sodium and water. This results in fluid buildup in the lower limbs. Identifying kidney impairment early allows for management strategies that can slow further decline and improve fluid balance.

Get A Kidney Function Test Here

2. Electrolyte Panel (Sodium, Potassium)

What it measures: This test evaluates the levels of key minerals in your blood that regulate fluid balance, nerve activity, and heart rhythm.

• Sodium controls how much water the body retains or eliminates.
• Potassium is involved in muscle function and cardiac activity.

Why it’s important: Abnormal levels may point to kidney or adrenal gland dysfunction. For instance, low sodium levels can indicate fluid overload or impaired kidney regulation, while imbalances in potassium can contribute to complications that worsen swelling and cardiovascular strain.

Book An Electrolyte Panel Here

3. B-Type Natriuretic Peptide (BNP)

What it measures: BNP is a hormone produced by the heart’s ventricles in response to excessive stretching caused by fluid overload.

Why it’s important: Elevated BNP levels are a hallmark of heart failure. In this condition, the heart struggles to pump effectively, leading to fluid backup in the legs and lungs. A high BNP can help confirm that swelling is related to cardiac dysfunction and inform urgent management decisions.

 Book A BNP Test Here

4. Albumin Test

What it measures: Albumin is a protein produced by the liver that helps maintain the oncotic pressure needed to keep fluid inside blood vessels.

Why it’s important: When albumin levels fall, fluid leaks into surrounding tissues, causing swelling. Low albumin may result from liver disease, kidney conditions that cause protein loss in urine (like nephrotic syndrome), or malnutrition. Identifying the cause allows doctors to treat the underlying issue and reduce fluid retention.

Book An Albumin Test Here

These blood tests help uncover imbalances or organ dysfunction that might not be apparent from symptoms alone. When reviewed alongside your medical history and physical findings, they enable your doctor to determine the cause of your swelling and guide treatment that targets the root issue.

If swelling is persistent, worsens over time, or is accompanied by other symptoms such as fatigue, shortness of breath, or weight changes, it is important to get evaluated without delay.

Get Tested Easily with Apollo 24|7

When your doctor recommends diagnostic tests to understand the cause of your swollen legs or ankles, choosing a trusted and convenient testing provider is paramount. Apollo 24|7 simplifies this process by offering a wide range of reliable lab tests. With accurate results delivered quickly, you and your doctor can work together to identify any underlying factors contributing to your symptoms and plan the right treatment.

Here’s why choosing Apollo 24|7 for your swelling investigations is a smart step:

• Comprehensive Test Panels: Apollo 24|7 offers a wide range of diagnostic tests relevant to investigating leg and ankle swelling. These include focused test packages such as the Kidney and Heart Function Panel, Electrolyte Panel, and Albumin Level Testing.
• NABL-Accredited Labs: Tests are conducted in high-quality labs certified by the National Accreditation Board for Testing and Calibration Laboratories (NABL), ensuring trusted accuracy and reliability for your results.
• Home Sample Collection: No need to travel; get blood samples collected conveniently from your home at a time that suits you, offering privacy and comfort.
• Easy Online Booking: Book your tests effortlessly through the user-friendly Apollo 24|7 app or website with just a few clicks.
• Fast Digital Reports: Receive secure, detailed reports swiftly online, delivered directly to your device, ready for your doctor to review.
• Trusted Brand: Benefit from the trusted expertise and healthcare legacy of Apollo Hospitals Group, one of India’s most respected medical networks.

By choosing Apollo 24|7, you gain access to high-quality, reliable, and convenient diagnostic services that can significantly streamline your journey towards understanding and effectively managing your constant leg and ankle swelling.

Conclusion

Swollen legs or ankles are more than just a visible symptom; they can be your body's way of communicating an underlying imbalance, particularly related to your kidney function, heart health, or protein levels. While mild swelling can have everyday causes, ongoing or unexplained fluid retention, especially when combined with other symptoms, should not be ignored. Blood tests such as a Kidney and Heart Test Package, along with checks for protein levels, can be essential in identifying possible organ dysfunction or nutritional imbalances. Getting an accurate diagnosis is crucial for finding effective, long-term relief. With the right information, your doctor can create a treatment plan that targets the root cause, helping you feel better and improve your overall health. If you are experiencing persistent swelling in your legs or ankles, speak with your doctor to see if these tests could help uncover the cause.