Lower Back Pain with Fatigue – When to Test Iron & Kidneys

Dr Lauren Holland • Marylebone Diagnostic Centre
Results within 24 – 42 hours. Westminster residents receive 20% off.

Lower back pain combined with fatigue is one of the most common complaints among London patients. Many people describe dull aching, heaviness around the lower spine, pain that worsens after standing or sitting, and exhaustion that does not improve with rest. While muscular strain is a frequent cause, lower back pain with persistent tiredness can also indicate iron deficiency, kidney issues, low vitamin D, thyroid imbalance, urinary inflammation or underlying infection.

Clinically, we see this combination daily – especially among people working long hours, commuting, carrying heavy bags, or recovering from illness. Blood testing is one of the fastest ways to understand whether back pain is mechanical or influenced by internal factors. This guide explains the common causes and the tests available at Marylebone Diagnostic Centre.

Why Lower Back Pain and Fatigue Happen Together

Lower back pain can originate from muscles, nerves, bones or organs.
Fatigue often comes from biochemical or hormonal changes.

Together, they strongly suggest:

Because the causes overlap, testing brings clarity.

Symptoms That Commonly Appear Together

Patients report:

• dull ache in lower back
• weakness or heaviness in legs
• stiffness in the morning
• fatigue despite normal sleep
• dizziness
• reduced endurance
• pain on one side (kidney-related)
• urinary discomfort
• bloating
• low mood
• cold sensitivity
• headaches

This pattern often points to nutrient deficiency or kidney involvement.

When Lower Back Pain Is Serious

Seek testing if you have:

• pain on one side
• fever with back pain
• burning urination
• blood in urine
• severe fatigue
• unexplained weight changes
• swelling in legs
• pain lasting more than 3–5 days
• dizziness or breathlessness

These may indicate kidney infection, iron deficiency or thyroid issues.

Risk Factors for Back Pain and Fatigue in London

You may be more likely to develop these symptoms if you:

• stand or sit for long periods
• have low vitamin D (very common in the UK)
• drink little water
• have heavy periods
• recently increased gym activity
• are under chronic stress
• sleep poorly
• carry heavy bags
• drink alcohol regularly
• work long hours or night shifts

Urban lifestyle patterns strongly influence this symptom pairing.

What Blood Tests Reveal

At Marylebone Diagnostic Centre, these tests help identify the cause.

Ferritin (Iron Stores)

Low iron is one of the most overlooked causes of:

• lower back pain
• muscle fatigue
• dizziness
• weakness

Especially common in women with heavy periods.

Kidney Function Test

Checks for:

• infection
• inflammation
• reduced filtration
• dehydration-related stress

Symptoms linked:

• pain on one side
• urinary changes
• fever

Vitamin D

Low levels cause:

• muscle weakness
• bone pain
• lower back discomfort
• fatigue

Extremely common in London, especially winter.

Thyroid Panel

Hypothyroidism leads to:

• back stiffness
• fatigue
• weight changes
• muscle weakness

Full Blood Count (FBC)

Checks for:

• anaemia
• infection
• inflammation

CRP

Helps detect:

• inflammatory causes of back pain
• kidney infection
• pelvic inflammation

HbA1c

Blood sugar imbalance leads to:

• fatigue
• heavy legs
• muscle aches

Vitamin & Mineral Profile

Important for identifying low:

• magnesium
• potassium
• calcium
• B12

All linked to muscle pain and weakness.

Wellness Profile

The most complete panel when symptoms are unclear.

Covers:

• kidney markers
• liver markers
• vitamins
• minerals
• thyroid
• FBC
• CRP
• HbA1c

Which MDC Profiles Are Best?

Symptom – Test Matching Table

Clinical Insight

“When fatigue and lower back pain appear together, we often find iron deficiency, kidney involvement or low vitamin D. Blood testing helps identify the true cause and prevents long delays.”
– Dr Lauren Holland

FAQs (People Also Ask)

Book Your Lower Back Pain Tests at Marylebone Diagnostic Centre

Marylebone Diagnostic Centre
73 Baker Street, London W1U 6RD
Tel: +44 7495 970109
Open Monday–Saturday, 08:00–16:00

Fast, private and confidential testing with results in 24–42 hours.
Westminster residents receive 20% off.

Quick Links

• Cardiac Profile
• HbA1c Test
• Full Lipid Panel
• Fatigue and Energy Profile
• Kidney Function Test
• Electrolytes Test
• Liver Function Test
• Thyroid Function Test
• Magnesium Test
• Full Blood Count
• Urinalysis & Culture
• Book an Appointment
• ECG Testing
• Wellness Profile
• Pancreatic Profile
• Advanced Sexual Health Panel
• STI Testing London

Read More

• NHS: Vitamin D Deficiency
• NHS: Thyroid Issues
• NHS: Back Pain
• NHS: Iron Deficiency
• NHS: UTIs