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When kidneys fail, waste builds up in the blood within days. Before the 1940s that usually meant death. Today, hemodialysis keeps many such patients alive, and the first working machine was built from sausage casing, wooden slats and an enamel tub in an occupied country at war. Here is Willem Kolff's story, the diffusion idea behind dialysis, a quick calculation of what healthy kidneys do, and what you can learn from how he worked.
Who was Willem Kolff?
An In Memoriam in the Texas Heart Institute Journal records that Kolff was born in Leiden, the Netherlands, on 14 February 1911 and died on 11 February 2009, three days before his 98th birthday. He qualified in medicine at Leiden in 1938.
According to the 2002 Lasker Award description, the idea began that year at the University of Groningen hospital, where Kolff watched a young man die slowly as waste built up in his blood. If only the poisons made each day could be taken out, he reasoned, such patients might live.
How did the artificial kidney work?
Kolff needed two things. The first was an anticoagulant so blood would not clot outside the body; heparin had become available. The second was a membrane. He chose cellophane sausage casing. Earlier researchers had shown that when two solutions are separated by cellophane, small molecules move from the higher concentration to the lower one.
So blood would run inside the cellophane tube, with rinsing fluid outside. Urea and other small waste molecules would diffuse out into the fluid, while blood cells and proteins, too big for the pores, stayed in. The more membrane area, the faster the cleaning.
The NCERT Class 11 Biology chapter on Excretory Products and their Elimination describes the same principle in today's machines: a coiled cellophane tube, a dialysing fluid with the same composition as plasma except the nitrogenous wastes, and heparin added to the blood.
How did he build it during the war?
When Germany invaded the Netherlands in 1940, Kolff's head of department, Polak Daniels, took his own life. Kolff left Groningen for the small town of Kampen. The Lasker description notes that materials were rationed, so he used glass tubing where he could not get rubber, and wooden slats when aluminium ran out. He had stocked up on sausage casing before the occupation.
With help from the director of a local enamel factory, he built a rotating drum kidney. About 100 feet of cellophane, roughly 30 metres, was wound round a horizontal drum turning in a tub of rinsing fluid. As the drum turned, blood moved along the tube and released its waste into the fluid. The Academy of Achievement biography dates the first crude artificial kidney at Kampen to 1943.
Why did the first 15 patients die?
Doctors referred only patients who were already in a coma and close to death. The Lasker description records that the first 15 patients died, but not from the treatment; Kolff could control their urea levels, and some woke briefly. In September 1945 a 67-year-old woman, a Nazi collaborator many locals wanted left untreated, became his first clear success. Her own kidneys recovered and she lived another seven years.
After the war, his Academy of Achievement biography notes, he shipped machines to Britain, Canada and the United States; he later worked at the Cleveland Clinic from 1950 and the University of Utah from 1967. In 2002 he shared the Lasker Clinical Award with Belding Scribner "for the development of renal hemodialysis, which changed kidney failure from a fatal to a treatable disease, prolonging the useful lives of millions of patients."
Worked example: how much do healthy kidneys filter?
NCERT gives a glomerular filtration rate of about 125 mL per minute.
Per hour. 125 × 60 = 7,500 mL = 7.5 L.
Per day. 7.5 × 24 = 180 L, which matches NCERT's figure of 180 litres a day.
Compare with urine. NCERT gives 1 to 1.5 L of urine a day. So over 99% of the filtrate is reabsorbed: 1.5 / 180 = 0.0083, under 1%.
A machine has to do the waste-removal part of this job in a few hours, which is why Kolff wanted as much membrane surface as possible.
Where does this sit in your syllabus?
Hemodialysis appears in NCERT Class 11 Biology under disorders of the excretory system, and fill-in-the-blank questions on dialysing fluid are common. Our post on excretory products for NEET covers the full chapter, and Thomas Graham and the diffusion law covers the physics of diffusion.
If diffusion through a membrane is easier to grasp when you can watch it, the Fermi Simulation Lab has interactive simulations for ideas that are easier to see than read.
What can a student learn from Kolff's way of working?
Turn grief into a question. One patient's death became a clear engineering problem: remove waste the kidneys could not.
Use what you have. Sausage casing, wooden slats and an enamel tub were not ideal, but they were available.
Expect early failures. Fifteen deaths could have ended the work. He looked at what had improved, such as urea levels, and kept going.
Share the tool. Sending machines abroad helped others improve on his design.
Next step: from memory, write the four things in NCERT's description of a dialysis unit, then check each against the chapter.
