Mitochondrial-Style Symptoms With Normal Labs

What the standard model gets wrong

The standard model relies on hematologic, metabolic, and inflammatory panels to detect disease. When those panels are normal in a patient with significant functional impairment, the conventional conclusion is that the impairment is not biomedical. The diagnostic codes available — chronic fatigue, somatoform, deconditioning — carry an implicit framing that the lesion is not at the substrate level.

The framing is not supported by the mechanistic literature. NAD+ depletion, mitochondrial Complex injury, and disrupted Krebs cycle flux are documented in the populations that present this way. They are detectable. They are treatable. The reason conventional panels miss them is that the panels were never designed to measure them.

The patient who hears "your labs are normal" and is told to exercise more is being managed against the wrong model. Premature exertion in this state produces damage, not recovery.

What the Host Capacity Model says about bioenergetic failure

Every cell that does meaningful work depends on mitochondrial ATP output. Mitochondrial ATP output depends on substrate availability (NAD+, FAD, oxygen, fuel), on Complex integrity, on iron-sulfur cluster assembly, and on the absence of inhibitory signaling (CD38 overactivity, inflammatory cytokines, oxidative damage). Each of these is a layer at which failure can occur.

The most common pattern in this presentation is sustained NAD+ depletion driven by chronic immune activation. CD38 overexpression consumes the NAD+ pool faster than salvage can replace it. PARP activation in response to oxidative or viral damage consumes additional NAD+. The result is a pool that is chronically below the threshold required for normal mitochondrial function.

Layered on this is Complex IV insufficiency in patients with prior viral injury or sustained inflammation. Complex IV is the terminal oxidase. When its activity is reduced, electron flow through the chain is constrained, lactate rises, and the cell cannot meet sustained energy demand. The clinical readout is post-exertional malaise.

Iron-sulfur cluster insufficiency is the third layer. Fe-S clusters are required for Complex I and III. NFS1 is the rate-limiting enzyme in their assembly. Dysregulation here — by inflammation, by certain dysbiotic states, by genetic variation — produces a Krebs cycle signature that is recognizable on organic acid testing.

Treatment is layered. NAD+ pool restoration is the foundation. Mitochondrial cofactor support — ubiquinol, B2, B3, carnitine, magnesium — provides substrate for the downstream enzymes. Iron, copper, and B-vitamin status need to be in the optimal range for Fe-S cluster assembly. And the upstream drivers of CD38 activation — chronic infection, dysbiosis, sustained inflammation — need parallel attention so that the recovery is not eroded as fast as it is built.

Patterns I look for in cases like this

• Functional impairment with a normal conventional workup.
• Post-exertional malaise with twenty-four to seventy-two hour delay.
• Morning function that declines through the day.
• Cognitive dimming that tracks with energetic state.
• Disproportionate response to alcohol, illness, or stress.
• Onset traceable to a viral event or to a sustained illness.
• Concurrent GI changes — dysbiosis, motility shift, food sensitivity.
• Elevated lactate or abnormal lactate-to-pyruvate ratio.
• Family history of similar unexplained patterns.
• Repeated antibiotic exposure preceding onset.

Tests I usually want to see

• Intracellular NAD+ panel — target above 500 μM, often below 350 in this population.
• Organic Acid Test — Krebs cycle intermediates, lactate to pyruvate ratio, oxidative stress markers.
• Serum lactate at rest and with measured exertion where feasible.
• Ferritin, iron, TIBC, ceruloplasmin, copper — Fe-S and Complex IV substrate context.
• Carnitine panel — fatty acid oxidation support.
• Inflammation panel — hs-CRP, IL-6, TNF-α.
• Methylation panel where one-carbon support is in question.
• Shotgun metagenomics and barrier markers — upstream driver context.

Leverage points

NAD+ pool restoration is the foundation. Sustained dose over months, not short courses. Oral NMN at sufficient dose is the broadly accessible route. IV NAD+ accelerates the timeline in resource-permitting cases. Either way, the pool needs to repleted to a level that supports normal Complex IV throughput and quiets CD38-driven turnover.

Mitochondrial cofactor support runs in parallel. Ubiquinol, B2, B3, carnitine, magnesium at clinical doses, sustained. These do not replace NAD+ restoration. They provide the substrate the recovering system needs in order to use the restored pool.

Upstream driver work is non-negotiable. As long as the inflammatory or infectious driver of CD38 activation is unaddressed, the NAD+ pool keeps being consumed. Dysbiosis treatment, barrier restoration, post-viral attention where relevant.

Pacing is mechanistic, not psychological. Exertion in a substrate-failed state produces real damage. Protected recovery — defined demand, defined rest, gradual increase — is what permits the rebuild. Standard graded exercise prescriptions that ignore the bioenergetic state can prolong illness substantially.

Where this account may be wrong

Primary mitochondrial disease with established genetic mutations follows a different trajectory and requires different management. Thyroid disease, anemia, and sleep disordered breathing produce overlapping symptoms and must be ruled out. The bioenergetic-failure account is offered for the population with this clinical pattern and a negative conventional workup — which is the population most commonly told nothing is wrong, and is most commonly correct that something is.

Frequently asked questions

Related reading

• The Host Capacity Model
• Colonocyte bioenergetics
• Long COVID as a mitochondrial injury
• Butyrate oxidation
• Oxygen gradient failure