What the experts found: Three independent haematologists (Prof. Giuseppe d'Onofrio, Dr Laura Garvican-Lewis, and Dr Jakob Mørkeberg) reviewed the profile anonymously and unanimously concluded that doping was the most likely explanation. They issued five separate expert opinions over four years, each time reaching the same conclusion. Their final verdict, in 2025: "The totality of ABP evidence leads to the unanimous conclusion that the Athlete's blood profile is highly likely the result of blood manipulation and highly unlikely due to any other cause."

The key red flags, explained:

– Sample 2 (Sept 2, 2018): High HGB + suppressed immature reticulocyte fraction (a classic pattern of recently discontinued EPO use.) Collected six days before a Prague 10km race in which Kipruto performed well.

– Samples 15-16 (May-June 2020): Elevated HGB with unusually low reticulocytes, which is the opposite of what would be expected during a low-training period. The panel said this pattern is consistent with EPO use.

– Sample 18 (Aug 31, 2020): Low HGB + elevated reticulocytes, which is consistent with blood withdrawal for later reinfusion.

– Samples 24-25 (June 5-16, 2021): Sharp rise in HGB and reticulocytes in the days immediately before the Kenyan Olympic Trials, consistent with ESA (erythropoiesis-stimulating agent) use.

– Samples 30-31 (Nov 2021 - Feb 2022): Large reticulocyte spike with falling HGB after 44 days at altitude, which is again consistent with blood withdrawal.

The probability of the five threshold-breaching results occurring by chance alone: approximately 1 in 10 billion.

The three defenses Rhonex Kipruto mounted—and why CAS rejected every one:

Explanation 1 – Alcohol abuse: Kipruto acknowledged drinking heavily, particularly during the COVID pandemic, and argued dehydration caused elevated HGB values. CAS rejected this. The Joint Expert Panel found that alcohol actually increases plasma volume—which would lower, not raise, HGB. The EtG (alcohol marker) values in his urine were also largely below meaningful thresholds, and two of the most flagged samples (Samples 2 and 15) showed no alcohol markers at all.

Explanation 2 – Irregular training and COVID disruption: The defense argued erratic training loads caused the blood value swings. CAS rejected this too. Exercise physiologist Dr Garvican-Lewis—whose expertise even Prof. Brandt conceded surpassed his own on this point—explained that the Adaptive Model is specifically designed to accommodate altitude residents and training variation. Normal seasonal fluctuation produces gradual, modest changes — not the abrupt, statistically extreme peaks and valleys seen in Kipruto's profile.

Explanation 3 – Primary Inherited Erythrocytosis (PIE/PFCP): The most sophisticated defense argument, was introduced late in proceedings. Kipruto's expert Prof. Stephen Brandt of Vanderbilt University argued that a combination of genetic variants—JAK2 L393V and HFE H63D—gave Kipruto a rare inherited condition causing hypersensitivity to EPO, which in combination with altitude training and alcohol use could explain the ABP abnormalities.

CAS dismantled this argument piece by piece:

• The key disease-defining EPOR mutation was not found in Kipruto.
• JAK2 L393V is classified as a "variant of uncertain significance" with no established functional data showing EPO hypersensitivity.
• If the condition were genetic, it would produce consistently elevated values across the entire passport—not dramatic peaks and valleys.
• The private blood tests used to establish the diagnosis were conducted in 2024, two years after the last ABP sample, at the request of Kipruto's own expert, and were therefore potentially susceptible to manipulation.
• The family history evidence (father and uncles with JAK2 L393V) established only a shared genetic variant, not an inherited erythrocytosis phenotype.

The competition correlation:

Beyond the statistical abnormalities, the panel found a clear pattern of flagged samples clustering around key competitive moments:

• Sample 2: Six days before Prague 10km, September 8, 2018
• Sample 20: Three days before Valencia Half Marathon, December 6, 2020
• Samples 24-25: Days before Kenyan Olympic Trials, June 17-19, 2021

The Panel concluded this confluence "amply demonstrated" a doping scenario.

The sanction: