Patients ask one question more often than any other. "Doctor, is my heart alright?" It deserves a proper answer rather than a vague one. Much of what we read online worries us about small things and stays quiet about the ones that matter. What follows is an attempt to explain, in plain words, what actually decides your heart health and what you can do about it.

For many years we judged heart health by cholesterol alone. We now understand that the heart, the kidneys and the way your body handles sugar and weight are all part of one system. Trouble in one usually means quiet trouble in another. Doctors call this cardiac, kidney and metabolic health. It is why this calculator asks about your kidney test and your sugar, not only your cholesterol. Looking at all of them together gives a far truer picture than any single number.

This is not a small difference and it is worth knowing. People of Indian and South Asian origin tend to develop heart disease about ten years earlier than people in Western countries, and often at cholesterol levels that a standard chart would call acceptable. A forty five year old man in Udupi with perfectly ordinary looking reports may still be carrying real risk.

Our body weight limits are also different. In Western charts, overweight begins at a body mass index of 25. For Indians it begins at 23, because we tend to carry fat around the abdomen and inside the organs even when the weight on the scale looks fine. If you select South Asian background in the calculator, it adjusts the result to account for this.

A coronary calcium scan is a quick CT that looks for hardened deposits in the heart arteries. It is most useful when the risk works out to be somewhere in the middle and you are undecided about starting a tablet. If the scan shows nothing at all, and you are not diabetic, it is usually reasonable to wait and watch. If it shows a score of 100 or more, the discussion is settled: there is deposit there, and treatment protects you. It is not a test everybody needs, and it is worth asking your doctor whether it would change anything for you before spending on it.

Sometimes the usual tests do not explain why heart trouble has occurred early in a family. In those cases a few extra tests can help. You do not need them for this calculator to work, and most people will never need them at all.

• ApoB and ApoA1. Cholesterol travels in tiny packets. ApoB counts the packets that leave deposits in the artery wall, and ApoA1 counts the ones that clear them away. Sometimes the ordinary cholesterol report looks fine while this balance is not.
• Lipoprotein(a). A sticky form of cholesterol you inherit from your parents. Diet and exercise barely change it. If it is high, we work harder on everything else to make up for it. It is worth testing once in a lifetime, particularly if a close relative had heart trouble young.
• hsCRP. A measure of quiet inflammation in the blood vessels. A deposit sitting still is one thing. An inflamed deposit is the one more likely to cause sudden trouble.
• Homocysteine. When this is high it can irritate the lining of the blood vessels. In our part of the country it is often simply a vitamin B12 deficiency, common in a strict vegetarian diet, and usually straightforward to correct.

It is easy to worry about the wrong things. Based on what the evidence shows, these are the ones that genuinely matter:

• Tobacco in any form. Cigarettes, beedi, gutka, khaini. Stopping is the single most powerful thing you can do, and the benefit begins within weeks.
• Blood pressure. It causes no symptoms until it causes damage. Get it checked even when you feel completely well.
• Blood sugar. Diabetes roughly doubles heart risk, and it is very common in our region.
• Waist size. Fat around the middle matters more than total weight. Losing even four or five kilograms improves the sugar, the pressure and the cholesterol together.
• Movement. Thirty minutes of brisk walking on most days is enough. It does not need to be a gym.
• Alcohol. You may have read that a daily drink protects the heart. That idea came from older studies that we now know were misleading, and the current evidence does not support drinking for the sake of your heart. The safest amount is none. If you do drink, keep it occasional and small, and never treat it as medicine. Alcohol also raises blood pressure and triglycerides, and in our region it is a common and often unrecognised reason for both.
• Sleep and stress. Both are real, and both are usually the first things we give up.

A high number is not a prediction of what will happen to you. It is a statement about a group of people who share your details, and it is an estimate, not a certainty. Most people in a high risk group live long and well, particularly once the risk is recognised and acted upon.

What the number really tells you is that you have something worth attending to, and time in which to attend to it. Almost every part of it can be improved. Take this page, or a printout of it, to your doctor and talk it through. That conversation is the point of the whole exercise.

This calculator is about the years ahead, not about today. Please do not use it if you are unwell right now. Go to a hospital immediately if you have chest pain or heaviness, pain spreading to the arm, jaw or back, sudden breathlessness, sudden weakness of the face, arm or leg, sudden difficulty speaking, or a cold sweat with unease. In a heart attack or a stroke, the first hour matters more than anything on this page.