# Persistent fatigue: what to check before considering NAD+

Fatigue can have several causes. Learn how sleep, symptoms and selected blood tests shape an evaluation before NAD+ enters the conversation.

Canonical: https://velri.co/blog/fatigue-labs-sandwich-caregiver-should-ask-before-reaching-for-nad
Publisher: Velri (https://velri.co/about)
Published: 2026-07-24
Updated: 2026-09-30
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Persistent fatigue can have several causes. Sleep loss, stress, iron deficiency, thyroid problems, medicines and sleep disorders can all contribute. The starting point is the pattern of symptoms, followed by tests that fit it. [1]

NAD+ helps cells carry out essential metabolic processes. That biological role does not establish that NAD+ treatment relieves unexplained fatigue. A review of NAD+ research describes substantial unanswered questions about how to restore levels safely and whether doing so benefits human aging. [2]

## Which tests answer useful questions?

A complete blood count can identify anemia. Iron studies, including ferritin, help assess iron stores when blood loss, diet or other findings suggest iron deficiency. Heavy periods and blood loss around childbirth are relevant history; so are gastrointestinal symptoms or previous digestive surgery. [1][3]

Thyroid testing may make sense when the broader history suggests a thyroid problem. Depending on the symptoms and examination, an evaluation can also include kidney and liver tests. There is no single blood panel that explains every case of fatigue. [1]

Vitamin B12 is another targeted question, especially with dietary restrictions, absorption problems or symptoms such as tingling and numbness. B12 deficiency can produce neurological symptoms even without anemia, so a normal blood count does not resolve every B12 concern. [4]

## The information a lab cannot supply

A week of notes about sleep opportunity, waking during the night, daytime sleepiness and when energy drops can make the conversation more specific. The medication and supplement list matters too: some products contribute to fatigue, and the timing may offer clues. [1]

For someone caring for children and aging parents, “I am tired” may mean too little sleep, physical exhaustion, or a change that persists despite rest. Those deserve different questions. MedlinePlus distinguishes fatigue, a lack of energy, from drowsiness, the need to sleep. [1]

## Sources
[1] Fatigue: MedlinePlus Medical Encyclopedia (2025). https://medlineplus.gov/ency/article/003088.htm
[2] NAD+ metabolism and its roles in cellular processes during ageing (2021). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7963035/
[3] Anemia - Iron-Deficiency Anemia | NHLBI, NIH (2022). https://www.nhlbi.nih.gov/health/anemia/iron-deficiency-anemia
[4] Vitamin B12 - Health Professional Fact Sheet (2024). https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

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