The Intern At Work: Internal Medicine
Sep 13, 2026 · 15 min · 8 segments
Send us Fan Mail In this episode, we break down an approach to proteinuria, focusing on the interpretation of the urine dipstick, the urine ACR, and…
Time for a minute physiology.
When the kidneys are perfused, proteins get filtered in the glomerulus, which is comprised of three layers, the fenestrated endothelium, the glomerular basement membrane, and the podocytes.
This lets us retain proteins in the plasma instead of transmitting them into the glomerular filtrate.
The structure of these components of the glomerulus dictate what substances are able to pass from the blood into the glomerular filtrate.
Venestrated capillaries in the endothelium filter particles by size, and the negatively charged basement membrane repels proteins which carry negative charge.
Lastly, podocytes serve as a final layer before the tubular fluid, further filtering the size of particles that are able to pass into the nephron.
The result is that larger, negatively charged components of the blood then exit the glomerulus, while other components including ions, water, urea, glucose, and creatinine pass through the glomerular filtration barrier.
The protein that does make its way into the urine is comprised of albumin, low molecular weight proteins such as immunoglobulins and light chains, and proteins that are secreted by the tubules themselves, such as IgA, urokinase, and tam-horseful mucoproteins, which form the scaffold for casts that are identified under urine microscopy.
it's important to remember that a small amount of proteinuria can be physiologic.
Less than 150 mg of total protein per day and less than 30 mg of albumin per day is thought to be within normal limits.
This corresponds to a urine ACR less than 3 mg per mmol and a urine PCR of less than 15 mg per mmol.
In a short while, we'll discuss what these tests mean and their usage.
In clinical settings, the first assessment of proteinuria usually takes the form of a urine dipstick, a functionally qualitative assessment that also offers a semi-quantitative assessment of proteinuria.
Importantly, there are common false positive and transient phenomena that can cause non-persistent proteinuria.
For example, urinary tract infections, recent exercise, hemoconcentration, hematuria and stones, menses in women, orthostatic proteinuria, and contrast, which causes a transient proteinuria, which is an important consideration in the inpatient setting.
Time for a minute physiology.
When the kidneys are perfused, proteins get filtered in the glomerulus, which is comprised of three layers, the fenestrated endothelium, the glomerular basement membrane, and the podocytes.
This lets us retain proteins in the plasma instead of transmitting them into the glomerular filtrate.
The structure of these components of the glomerulus dictate what substances are able to pass from the blood into the glomerular filtrate.
Venestrated capillaries in the endothelium filter particles by size, and the negatively charged basement membrane repels proteins which carry negative charge.
Lastly, podocytes serve as a final layer before the tubular fluid, further filtering the size of particles that are able to pass into the nephron.
The result is that larger, negatively charged components of the blood then exit the glomerulus, while other components including ions, water, urea, glucose, and creatinine pass through the glomerular filtration barrier.
The protein that does make its way into the urine is comprised of albumin, low molecular weight proteins such as immunoglobulins and light chains, and proteins that are secreted by the tubules themselves, such as IgA, urokinase, and tam-horseful mucoproteins, which form the scaffold for casts that are identified under urine microscopy.
it's important to remember that a small amount of proteinuria can be physiologic.
Less than 150 mg of total protein per day and less than 30 mg of albumin per day is thought to be within normal limits.
This corresponds to a urine ACR less than 3 mg per mmol and a urine PCR of less than 15 mg per mmol.
In a short while, we'll discuss what these tests mean and their usage.
In clinical settings, the first assessment of proteinuria usually takes the form of a urine dipstick, a functionally qualitative assessment that also offers a semi-quantitative assessment of proteinuria.
Importantly, there are common false positive and transient phenomena that can cause non-persistent proteinuria.
For example, urinary tract infections, recent exercise, hemoconcentration, hematuria and stones, menses in women, orthostatic proteinuria, and contrast, which causes a transient proteinuria, which is an important consideration in the inpatient setting.
The rest of this transcript — segmented and speaker-labeled, so you land on the exact moment something was said
Search every transcript — by keyword, by phrase, or by meaning, across every show Radar indexes
Trends — what is surging across podcasts, measured against its own baseline
Alerts — when a name you follow appears in a newly indexed episode
No account is needed to search Radar.
