In life underwriting, some of the most consequential decisions arise from medical gray zones – situations that lack clear answers, specifically clinical uncertainty, ambiguous test results, and unclear treatment guidelines.
These cases challenge insurance professionals to distinguish between findings that are acceptable as presented and those that require a deeper review.
The following are three case examples that illustrate this point. At first glance, each may appear manageable or of low concern, yet each also demonstrates why risk assessment should not stop at the first plausible explanation. The question is not “Is there an abnormality?” Instead, it is “Does the available evidence support a benign explanation, or is there a reasonable possibility of a more serious underlying condition?”
Estimated glomerular filtration rate (eGFR), as its name suggests, is an estimate of kidney filtration versus a direct measurement. eGFR equations were developed because chronic renal failure is a major cause of morbidity and mortality, and serum creatinine alone is not a strong early marker of renal function. As kidney function declines, the body can compensate by increasing creatinine excretion, allowing serum creatinine to remain within normal limits until renal disease is advanced. eGFR can help identify the risk earlier.
This case involves a 54-year-old female non-smoker with a body mass index (BMI) of 29. She had a history of high blood pressure (BP), for which she was taking ramipril (5 mg twice per day) and hydrochlorothiazide (25 mg once daily), and elevated cholesterol, for which she was taking atorvastatin (10 mg once daily). During the exam, her BP was slightly high – 145 over 90 – and a serum creatinine blood test was elevated at 92 µmol/L (normal is 45-90). This led to an eGFR, using the modification of diet in renal disease (MDRD) equation, of 55 mL/min/1.73m2 (normal is >60).
The gray zone appears when an eGFR result is mildly abnormal, but the surrounding evidence does not support kidney damage. In this case, the urine protein-to-creatinine ratio was 12.8 mg/mmol (normal is <20) and the urine albumin-to-creatinine ratio was 2.5 mg/mmol (normal is <3.0).
The underwriting insight was that the issue may have been with the equation, not the applicant.
MDRD is reasonably accurate in people with renal disease but less accurate when eGFR is normal or near normal, which is common in insurance populations. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is more accurate when renal function is normal or near normal, making it more useful in many insurance underwriting contexts.
In the case described, the same serum creatinine produced an eGFR of 55 using MDRD, 64 using CKD-EPI, and 84 using the Mayo quadratic equation, which is yet another available equation. With clear urine results and normal values under two equations, the case was accepted as standard.
The broader takeaway is practical: A mild eGFR abnormality should be interpreted alongside the equation used and other evidence of renal damage. If advanced kidney disease is present, MDRD, CKD-EPI, and Mayo tend to work equally well. But in the typical insurance population, where significant renal impairment is less common, CKD-EPI is the recommended approach because it provides a more accurate representation of eGFR in a normal population.1
Iron deficiency anemia is another impairment that can seem straightforward until the record conveys a more complicated story. For this case, a 52-year-old female non-smoker applying for a 19-year term policy had a history of hypothyroidism and iron deficiency anemia with no identified cause. She had been medicating with ferrous sulphate (200 mg three times a day as needed) and reported both a negative endoscopy and ultrasound, although an abdominal ultrasound did not appear in the general practitioner report (GPR).
A family history showed her father had diabetes at age 21 and ischemic heart disease at 63. The blood pattern also raised concern. She had a history of microcytic hypochromic anemia, consistent with iron deficiency anemia. She had symptoms – such as fatigue, shortness of breath, and pallor – and responded to oral iron. Her hemoglobin repeatedly improved with iron therapy and fell once iron stopped. When her hemoglobin was again abnormal, she applied for insurance one day following this abnormal blood test. Her gastroenterologist arranged both a gastroscopy and a colonoscopy, but while the gastroscopy was normal, no colonoscopy report was found.
It was later learned that her husband was a general practitioner at her general practitioners’ clinic. He ordered some of her blood work and the gastroscopy report was directed to him. His involvement in her care was reason for caution and independent documentation.
The overarching question was, “What is the cause of her recuring anemia?” Two considerations – anemia of chronic disease and thalassemia minor – were eliminated due to a lack of history regarding these conditions. A vegan diet was a possibility; however, the records did not document such a diet. Additional options include blood loss and celiac disease.
This is where gray zone thinking becomes essential. For underwriting, the goal is not always to identify the exact medical cause but to determine whether the evidence supports a benign cause or if a sinister cause remains plausible.
In this case, several factors raised a concern: The applicant was 52 and menstrual blood loss was absent and probably not a cause at this age. She had recurrent anemia that responded to iron but then returned when the iron was stopped, had ongoing three-month follow-up visits re her reoccurring anemia, and appeared to have an incomplete workup with no colonoscopy documentation.
The eventual outcome underscored the risk. The case was accepted as a standard risk with a mild anemia. Later, she presented with a terminal illness claim for metastatic adenocarcinoma of the colon and died shortly thereafter. The retrospective lesson was clear: Anemia should be rated for cause, and recurrent, new-onset iron deficiency anemia in a 52-year-old with an incomplete gastrointestinal workup should not be treated as a routine, mild anemia case.
White coat hypertension – a condition where BP is high when measured in a medical setting but normal or low when taken outside of a medical facility – is increasingly encountered in underwriting, but the term can be misapplied.
In this case, a 54-year-old man requesting life insurance in 2022 reported hypertension diagnosed in 2018 but claimed he was fully recovered. During the paramedical, his BP was high across three readings – 194 over 98, 171 over 99, and 189 over 99 – and his urine had no abnormalities. He reported that his BP rose during health screenings and medical visits but read as normal at home. He also revealed having been treated previously with ramipril (for his high blood pressure), but his physician discontinued it after two years because his BP was too low and it caused him to collapse. The family history revealed his dad had an MI at the age of 49.
The GPR complicated the story. It stated that hypertension had been diagnosed in late 2017 and that the applicant weaned himself off the medication in 2021. The GPR also noted 12 home BP readings averaging 137 over 85 and advised continued monitoring. The report omitted the type of cuff used during the home readings. A cuff applied over the wrist tends to be popular but is less accurate, while one on the upper arm is more precise. There was also no indication of an EKG or stress test to provide evidence of hypertensive heart disease.
The applicant’s own explanation, the GPR’s description, the paramedical readings, and tests not conducted, along with a family history of coronary artery disease, did not align cleanly.
Based on both the home and paramedical readings, the applicant had hypertension, as his BP was >130/80.
Both the client and the GP stated the client had white coat hypertension, yet they were missing the fact that he had hypertension – but it was not clear how severe this was. To support a final diagnosis of white coat hypertension or even hypertension requires further evidence. Additional home readings can help but could be reported incorrectly, either intentionally or unintentionally. Ambulatory 24-hour BP readings, where a cuff is worn for 24 hours, are considered the gold standard for a diagnosis of white coat hypertension and, in this man’s case, would have confirmed a diagnosis of hypertension.
The mortality implications are material. Untreated white coat hypertension is associated with a 36% heightened risk of cardiovascular events – such as heart attack and stroke – increased cardiovascular mortality, and about a 33% upsurge in all-cause mortality.2 Meanwhile, treatment of white coat hypertensives has shown cardiovascular morbidity and mortality similar to those without elevated blood pressure.
The case was ultimately accepted at standard; however, there are a range of underwriting approaches that could be justified in this medical gray zone. The elevated blood pressure readings recorded at the paramedical examination could have supported either a significant rating or a postponement while additional assessment or treatment was pursued. Another reasonable approach would have been to obtain three office blood pressure readings from the applicant's family physician and make a decision based on those findings, a process that would likely have resulted in a postponement. If challenged, 24-hour ambulatory blood pressure monitoring could have been recommended by the insurer to clarify the applicant's true blood pressure profile.
Across these cases, the recurring discipline is to avoid relying too heavily on the most convenient explanation.
For insurers and reinsurers, these examples reinforce the value of case-level judgment. Manuals and thresholds are indispensable, but they must be applied to the entire record. In gray zones, the most important information may be what is missing: a colonoscopy report, documented blood pressure trends, details on cuff type, or corroboration of a medication change. The absence of that information can itself be a risk signal.
Medical gray zones require more than mechanical application of underwriting rules. They call for evidence-based interpretation, attention to inconsistencies, and a willingness to pause when the record does not support a benign conclusion.
Gray zones are where disciplined risk assessment matters most. The best decisions come from asking not only what the available data shows, but also whether the missing data could change the outcome.
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