Values Of Laboratory Data In Diagnosis

Diagnosis is both an art and science in modern medicine. Physicians’ intuition, experience, and interaction with patients are the art, and laboratory values are the science. Hence, laboratory investigations become the heart of diagnosis that are essential in confirming, supporting, or ruling out clinical impressions. A simple blood test or blood sugar test or complex genetic markers can provide objective evidence that often provides concrete evidence that transform clinical judgment to a definitive diagnosis. No doubt laboratory values have tremendous contributions in clinical medicine; their interpretation demands context, understanding, and cautious explanation. 

Laboratory testing is the basis of any diagnosis in modern medicine. In previous times, when laboratory testing was not developed as today, diagnosis heavily relied on symptoms described by the patient and physical signs. However, such diagnosis often used to be misleading or ambiguous. For example, the same symptom can be due to various illnesses, such as fatigue that may result from diabetes, thyroid ailment, or stress. Hence, laboratory investigations help the provider in differential diagnosis and reach a definitive conclusion.  

Evidence-based medicine

Laboratory investigations serve as an important basis for evidence-based medicine. These values help not only in emergency settings but also in preventive care and help providers to reach life-saving decisions. In acute conditions, the elevated troponin level indicates cardiac injury, positive culture or raised white blood cell count gives positive impression of infections and causative pathogen. Similarly, in chronic cases, HbA1c values provide diabetes status and renal creatinine serves important indication of renal status. Hence, laboratory values not only serve as a diagnostic adjunct but also an essential for overall clinical management. 

The laboratory values are reproducible and quantifiable; hence, they are objective. The correct interpretation of those values not only reduces diagnostic uncertainty but also helps providers to reach a definitive diagnosis. A patient may exaggerate or underreport their experience; however, the lab values give concrete evidence. A person may deny taking a drug while driving but the laboratory investigation provides positive indication or a creatinine level gives definitive status of the renal system. 

Sometimes, laboratory values give false impression; therefore, they must be interpreted along with clinical symptoms. Elevation of liver enzymes may not always be due to liver disease but may be the result of drug interactions, muscle injury, or intense exercise. Therefore, it is always prudent to interpret the values by integrating the patient’s history and clinical symptoms.  The laboratory values come with a reference range, the number within which 95 per cent of values fall for a healthy individual. The reference range is a vital benchmark, but it is not absolute. Several factors influence the laboratory results, such as age, sex, ethnicity, or even hydration status. The higher hemoglobin level is found in people residing at high altitude owing to exposure to a chronic low oxygen level and normal creatinine levels may vary between professional athletes or elderly people. 

It is, therefore, essential to consider patient-related factors before reaching to a conclusive diagnosis. A person who walked for a few hours before measuring fasting blood glucose may give a false impression about diabetes or a person with stress or sleep deprivation may show elevated blood glucose. In the last few decades, there have been remarkable advances in laboratory technology. The accuracy, speed, and accessibility of lab results have improved due to automation, molecular diagnostics, and point-of-care testing. 

The modern automated analyzers can process samples in bulk and minimize human error, providing results quickly and in real time. People can now test pregnancy, blood glucose outside hospital settings, which has helped both healthcare workers and patients. The laboratory medicine has recently been utilising emerging technologies such as artificial intelligence and machine learning. Even before any symptoms develop, algorithms can analyse data to predict diseases. With the help of such technology, cancers are being diagnosed before any clinical symptoms. Hence, these innovations have helped laboratory medicine in predicting diseases long before clinical manifestations. 

The laboratory values give tremendous advantages in modern medicine; however, they should not be overly dependent. There might be errors in any stage, from pre-analytical, analytical, to post-analytical. The results can be distorted owing to a fault in sample collection, contamination during or post-collection, or delays in transportation. Similarly, discrepancies may occur between laboratories, status of equipment calibration, and quality of reagents. Therefore, standardization, calibration, and quality control systems play a crucial role in those values. 

A non-medical person may panic due to slightly raised result as home testing kits are widely available and they are unaware of clinical correlation and biological variability. At the same time, they may ignore significant abnormalities thinking of minor changes. Thus, it is recommended to guide them properly before utilising home test kits and interpret only with the help of a provider. 

Economic implications 

Although laboratory investigations have benefits, they also carry economic implications particularly in developing economies. Both patients and healthcare settings get overburden due to over and often unnecessary testing. Sometimes, minor abnormalities recorded due to over-testing can trigger cascades of further tests. At the same time, under-testing or neglect in essential tests can result in delayed diagnosis and impact negatively on outcomes. 

Therefore, providers must balance essential tests and cost effectiveness. Every test recommended should be rationally justified and test results should only be revealed to concerned people. In case of countries like ours, infrastructure, equipment, and training are paramount. Rural health centres still lack modern equipment and rely on outdated equipment. As telemedicine is expanding, laboratory data must integrate with a digital platform for speedy, cost-effective, and accurate results. At last, laboratory data help modern medicine by providing objective, reproducible, and accurate measurements of different parameters. But they should be carefully interpreted with patient variability and existing symptoms. There should be harmony between laboratory data, medical reasoning, and human empathy to reach the best diagnosis to provide effective treatment. 

(Dr. Lohani is the clinical director at the Nepal Poison Information Centre. lohanis@gmail.com)