Health Is a Continuum, Not a Binary State

There is binarity to the way we speak about health - you are either healthy or you are sick; your test is either normal or abnormal; you either have a disease or you do not. The language is simple, the categories are convenient and the healthcare system has largely been built around them. Unfortunately, human biology is not so accommodating of this binarism because we have a biological system that is constantly responding to genetics, age, environment, behaviour, nutrition, sleep, stress and time. Between the two labels of healthy and sick are gradients of risk and therein lies most of human health - there are periods of resilience, early biological changes, thresholds, symptoms, diagnoses, recoveries and deteriorations. The challenge for modern preventive healthcare in Nigeria is for people to understand this continuum better.

A person can feel perfectly well while blood pressure is gradually rising, insulin sensitivity is deteriorating, or kidney function is beginning to decline and none of these changes necessarily produces a symptom at the moment it begins. Hence, there may be no dramatic boundary separating the apparently healthy person from the patient but a series of small biological changes, unfolding quietly over months or years, until eventually the accumulated changes cross a threshold at which disease becomes clinically recognisable.

This distinction matters because the world's health burden is increasingly being shaped by diseases that behave precisely this way. The latest WHO mortality estimates show that non-communicable diseases killed at least 43 million people in 2021 i.e 75% of deaths unrelated to the covid pandemic. Eighteen million of those deaths occurred before the age of 70, with 82% occurring in low-and middle-income countries. Cardiovascular disease accounted for at least 19 million deaths. These figures describe the scale of a slow-moving biological and economic crises and so the question is increasingly not whether disease exists, but when we recognise that the biological process has begun.

Laboratory result reference ranges

Normal Vs Abnormal laboratory results

As a medical laboratory scientist, I have always found the word normal more complicated than it appears. A laboratory reference interval is not a declaration that a person is healthy because it is generally a statistical description of values observed in a defined reference population under defined conditions. Ideally, clinical interpretation requires much more such as the patient's history, risk factors, symptoms, medications, examination findings and, importantly, the context in which the measurement was obtained. Consider two people whose fasting glucose is 98 mg/dL. On paper, they have the same result, but assume one person's value has remained close to that level for several years while the other's has moved steadily upward from substantially lower levels. You will notice the numbers are identical today, but their trajectories are not. This is why a result can be within the reference interval and still deserve attention.

Establishing your personal baseline

One of the most underused assets in preventive medicine is a person's own previous health data obtained through diagnostics - testing and imaging. The first set of health data becomes a reference point, also known as a baseline - a picture of your health at a particular period against which subsequent measurements can be interpreted. For someone who has never measured their fasting glucose or HbA1c, there is no personal history against which future change can easily be compared. The same principle applies across cardiovascular, renal and other areas of health, although the appropriate biomarkers and frequency of measurement will differ according to age, sex, medical history, family history and individual risk.

We can now understand why longitudinal biomarker tracking deserves greater attention and this is the bone of what we are building at The White Coat, an infrastructure of Health Intelligence for tracking and monitoring key biomarkers so that our clients can identify risks early before it becomes pathological. This does not mean turning every little biomarker deviation into a disease, nor does it mean encouraging people to chase every biomarker in search of perfect health ( On the contrary, indiscriminate testing can create anxiety, false positives and unnecessary interventions).

Our message is clear - silent biological risk is common enough that waiting for symptoms is an inefficient strategy. Contrary to what many lay men may think, the absence of a diagnosis is not necessarily evidence of the absence of biological change or like I love to say, the absence of symptoms is not the presence of health. Some of the most important conditions in modern medicine can remain silent for years before symptoms appear. WHO estimates that 1.4bn adults aged 30–79 worldwide had hypertension in 2024, yet about 600m - 44% - were unaware that they had it. Only about 320m, or 23%, had their blood pressure under control.

Disease is a process, not an event

The most important idea that preventive healthcare needs to communicate more clearly is that disease is often a process before it becomes a diagnosis. There is a difference between the beginning of a disease process, the emergence of measurable risk, the crossing of a diagnostic threshold and the appearance of symptoms; and these events can be separated by years. For example, type 2 diabetes does not begin on the morning a laboratory report first crosses a diagnostic threshold, likewise, chronic kidney disease does not suddenly appear when a patient is finally told that kidney function is impaired.

The diagnostic threshold is important because doctors need thresholds at which action becomes justified, standardised and reproducible, but a threshold should not be mistaken for the moment at which biology itself began to change. Medicine has historically been very good at responding once the threshold has been crossed but the greater opportunity for preventive healthcare is to become better at understanding what happens before it.

Nigeria cannot afford a purely reactive model

Nigeria faces a particularly interesting version of this challenge because our healthcare system is managing two realities simultaneously. Communicable diseases remain major causes of illness and death, at the same time, NCDs are becoming an increasingly important part of the country's health burden. WHO's current country data estimate that NCDs accounted for 27.7% of deaths in Nigeria in 2021, while the organisation's broader 2023 disease outlook estimated that NCDs accounted for 27% of deaths in 2019. This changing landscape creates a difficult question for a country where healthcare resources are finite - how do we identify and manage disease earlier without simply making healthcare more expensive and more complicated?

Although Nigeria cannot afford to screen everybody for everything like Japan does through her Ningen Dock program, we can make preventive care risk-based, targeted and continuous enough to reap the biological and economic gains - detect and prevent diseases, with an eventual reduction in healthcare expenditure.