Not merely puffy feet: what pedal oedema can signify about your health

Pedal oedema, pedal from the Latin pedalis, meaning “pertaining to the foot” and oedema from the Greek oidēma, meaning “to swell” literally means swelling of the feet. This is a fairly common symptom, but one that generally has physicians delving deep, to identify the underlying cause. It can be caused by a variety of diseases: these can be systemic, due to cardiac, renal or liver disease, or may be local, caused by trauma.

Understanding pedal oedema

Pedal oedema is considered a premonitory symptom for many diseases. Understanding it involves firstly, classifying it. The first major classification is whether it is unilateral or bilateral, or, present on one or both feet. In case of single-sided pedal oedema, a local cause needs to be considered. This can range from trauma to the leg, lymphatic obstruction or even deep vein thrombosis or a mass compressing the leg’s venous supply, which needs expert consultation and radiological investigations.

Bilateral pedal oedema could portend something bigger. A famous quote of medical professors is: “Bilateral pedal oedema means all failures – cardiac, renal, liver, respiratory”. This grim line highlights the importance of detailed investigations into the cause of pedal oedema involving both limbs.

How does swelling happen?

Water makes up about 60% of an adult human body by weight. This water is divided: two-thirds of it is located within our cells (intracellular) while one-third of it is outside the cells (extracellular), and part of this extracellular water is in the vascular chamber. The vascular chamber is governed by the Starling equations of hydrostatic and oncotic pressure. When the hydrostatic pressure increases, as in the case of heart failure, water from the vascular chamber is pushed out, into the interstitium (supporting or connective tissues) causing oedema. Likewise, when the oncotic pressure decreases, as in low albumin states of chronic kidney disease and chronic liver disease, the fluid is pulled out into the interstitium.

There are also two other causes of oedema. One is endothelial injury (damage to the inner lining of blood vessels), as seen in trauma and other gravely sick conditions needing ICU admissions. The other is lymphatic stasis as is seen in Wuchereriasis or filariasis, colloquially known as elephantiasis.

Apart from these two conditions, a gross deficit in calories and protein over a prolonged period causing a nutritional deficiency condition known as beriberi, can cause pedal oedema. It can also be caused by the ingestion of food that is rich in sodium, leading to a sodium overload.

Other causes

A middle-aged woman had recently been diagnosed with hypertension, and was duly instructed by her doctor to take antihypertensives daily. The doctor warned her that if she developed pedal oedema, it was a sign of “heart damage due to uncontrolled hypertension”. The patient returned after four weeks of being on medication, tormented with pedal oedema. She said she had taken all her medications as prescribed, but even then, had developed pedal oedema. This turned out to be a case of drug-induced oedema, caused by one of her medications.

A large number of drugs can cause oedema by renal vasoconstriction or arteriolar dilation or by augmented renal sodium reabsorption. Irrespective of the cause, patients must ell their doctors about what medications they are on.

A few rarer causes of oedema include hypothyroidism, endocrine cortisolism (abnormally high or low levels of cortisol) and taking steroid tablets. Pregnancy is a common cause of pedal oedema, especially towards the later trimesters; however, it is best to consult your doctor about it, to ensure it is not indicative of the potentially dangerous condition of preecclampsia.

Thus, pedal oedema, or foot swelling, is a symptom—not a disease— that can be caused by a range of systemic or local conditions. Do not ignore it or try home remedies. A thorough evaluation by a healthcare professional is essential to determine its cause and treat it.

(Dr. Arvind Radhakrishnan is a general medicine practitioner, and an IAS officer trainee who simplifies complex health issues. arvindradhakrishnan97@gmail.com)