PROF Essam Elnadi LAB

13/09/2026

Causes of falsely elevated or lowered HbA1c

Falsely elevated or lowered HbA1c results occur when conditions alter red blood cell lifespan, turnover, or hemoglobin structure, making the test unreflective of true average blood glucose.

Causes of Falsely Elevated HbA1c
* Iron deficiency anemia: Extends red blood cell lifespan, which gives hemoglobin more time to bind with glucose.
* Vitamin B12 or folate deficiency: Slows down red cell production, aging existing cells and raising the percentage.
* Splenectomy: Removing the spleen stops the destruction of older red blood cells, prolonging their circulation time.
* Hemoglobin variants: Certain structural traits (like HbD, HbE, or specific mutations) interfere with laboratory assay readings.
* Uremia / Chronic kidney disease: Carbamylated hemoglobin builds up in the blood and can mimic or co-elute with HbA1c on specific lab platforms.

Causes of Falsely Lowered HbA1c
* Acute or chronic blood loss: Rapid blood loss forces the body to produce new, young red blood cells that have had less exposure to glucose.
* Hemolytic anemia: Destroys red blood cells prematurely, shortening their lifespan below the normal window.
* Recent blood transfusions: Introduces donor red blood cells that dilute the patient's own glycated hemoglobin sample.
* Advanced chronic kidney disease / End-stage renal disease: Shortens red cell survival and often involves erythropoietin treatments.
* Splenomegaly: An enlarged spleen increases the destruction rate of red blood cells.
Repeat testing using second sample if results are the same use alternative tests like fructosamine or continuous glucose monitoring might give you a clearer picture.
Recent HbA1c measuring using HPLC
markedly reduce these errors especially with Hb variants.

13/09/2026

Causes of absence of glucose in urine with high glucose in blood in elderly patients.

An absence of glucose in the urine despite high blood glucose in elderly patients is primarily caused by an elevated renal threshold for glucose that occurs with normal aging.
Key Causes and Mechanisms Increased Renal Threshold:
* As people age, the blood glucose concentration required for the kidneys to spill sugar into the urine increases. Blood sugar must reach much higher levels than in younger adults before glucose appears in the urine.
* Advanced Chronic Kidney Disease (CKD): Reduced kidney function and a lower estimated glomerular filtration rate (eGFR) mean that the kidneys filter blood and transport solutes differently, often reducing the filtered load or blunting the excretion of glucose despite elevated systemic levels.
* Severe Dehydration and Low Urine Output: Elderly patients with high blood sugar often experience osmotic diuresis leading to severe dehydration. When overall urinary output drops drastically (as seen in hyperosmolar hyperglycemic state), urinary markers like glucose can become falsely minimal or absent on spot tests.
* Impaired Glomerular Filtration: Reduced cardiac output or age-related vascular changes in the kidneys decrease the rate at which blood is filtered through the glomeruli, lowering the amount of glucose delivered to the renal tubules.

Summary:
Absence or appearance of glucose in urine depends on renal threshold which is normally 180 mg/dl. Glucose normally is filtrated from renal glomeruli into renal tubules to be reabsorbed by tubules to the blood. Glomerular disease will lead to absence of glucose from urine with high blood sugar, while tubular disease leads to renal glucosuria.

13/09/2026

Why some results of ESR and CRP are different in some patients

It is very common for Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) results to mismatch in the same patient. While both are blood tests used to detect systemic inflammation, they function through entirely different physiological mechanisms, leading to a phenomenon known as “laboratory discordance”.
The primary reasons these results differ include:

1. Different Time Windows (Kinetics)
The most significant reason for differing results is the speed of change.
* CRP acts like "breaking news". It is a direct protein manufactured by the liver that spikes sharply within hours of inflammation or infection and drops quickly once the trigger is resolved.
* ESR acts like "yesterday's newspaper". It is an indirect physical measurement of how fast red blood cells settle in a tube over an hour. Because it relies on the slow accumulation and clearance of heavy proteins like fibrinogen, ESR takes several days to rise and can remain elevated for weeks after a patient has fully recovered.
* Clinical Example: A patient recovering from an acute infection might show a normal CRP (resolved) but a high ESR (lagging behind).

12/09/2026

12/09/2026

12/09/2026

He spent his days sleeping beside a cold, wet wall… so I built him ...