Common Investigation Panels

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In clinical practice, investigations are sometimes grouped together into “sets”, “panels” or “screens” that focus on specific clinical presentations (e.g. confusion/anaemia). The aim of these screens is to rule common causes of a given clinical presentation in or out. It is worth having some knowledge of what tests are included in each of these investigation panels, so we’ve summarised some of the most common screens below.

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Confusion screen

Clinical assessment

Vital signs: sepsis/hypotension

Clinical examination:

• Level of consciousness (e.g. GCS/AVPU)
• Evidence of head trauma
• Sources of infection (e.g. suprapubic tenderness in urinary tract infection)
• Asterixis (e.g. uraemia/encephalopathy)

Lab tests

Full blood count: raised WCC may indicate infection

CRP: often raised in the context of infection

U&Es: uraemia/hyponatraemia

Bone profile: hypercalcaemia/hypocalcaemia

B12 & Folate: deficiency can cause confusion

Thyroid function tests: confusion is more common in hypothyroid states

Glucose: hypoglycaemia is a common cause of confusion

LFTs: confusion can occur secondary to liver failure (hepatic encephalopathy)

Coagulation/INR: particularly important for those patients on anticoagulation who may have had an intracranial bleed

Other investigations

CT head: if there is concern about intracranial pathology (bleeding, ischaemic stroke, abscess)

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Anaemia screen

Clinical assessment

Vital signs: hypotension and tachycardia may indicate active bleeding

Clinical examination:

• General pallor/conjunctival pallor
• Clinical signs of malignancy (e.g. abdominal mass/cachexia)
• Rectal examination: malaena/malignancy

Lab tests

Full blood count: will provide haemoglobin level/MCV/haematocrit/platelet count

Thyroid function tests: hypothyroidism can cause macrocytic anaemia

U&Es: chronic kidney disease can cause anaemia (due to reduced erythropoietin production)

Haematinics:

• B12 and folate: deficiency causes a macrocytic anaemia
• Ferritin
• Serum iron
• Total iron-binding capacity (TIBC)

Other investigations

Colonoscopy/gastroscopy: may be appropriate if there are concerns regarding gastrointestinal blood loss

CT chest, abdomen and pelvis: if there are concerns about malignancy

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Sepsis screen

Clinical assessment

Vital signs: blood pressure, pulse, respiratory rate, oxygen saturation and temperature

Clinical examination:

• Assessing for potential sources of sepsis (e.g. chest/urine/skin/intra-abdominal)

Lab tests

Full blood count: raised WCC may suggest infection

CRP: often raised in the context of infection

U&Es: acute kidney injury is common in sepsis

Lactate: raised in sepsis secondary to reduced end-organ perfusion

Blood cultures: to enable the causative organism to be identified

Other investigations

Urine sample: dipstick and culture

Sputum sample: culture

Stool sample: culture

Wound swab: culture

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Hyponatraemia screen

Clinical assessment

Clinical examination:

• Assessing current hydration status (hypervolaemia/euvolaemia/hypovolaemia) is important to help narrow the differential diagnosis of hyponatraemia

Lab tests

U&Es: to assess the degree of hyponatraemia, other electrolytes and renal function

Serum osmolality + urine osmolality + urinary sodium/potassium: useful for confirming a diagnosis of SIADH

Thyroid function tests: hypothyroidism can cause hyponatraemia

Serum cortisol: Addison’s disease is a potential cause of hyponatraemia

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Hypocalcaemia screen

Clinical assessment

Clinical examination:

• Assess current hydration status
• Assess urine output

Lab tests

U&Es: to assess other electrolytes and renal function

Bone profile: to assess calcium and phosphate levels

Ionised calcium

Parathyroid hormone (PTH): hypoparathyroidism is a potential cause of hypocalcaemia

Vitamin D: deficiency is a cause of hypocalcaemia

LFTs: to assess albumin level

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Refeeding syndrome screen

Clinical assessment

Clinical examination:

• Nutritional status: intake/output
• Fluid status

Lab tests

U&Es: hyponatraemia/hypokalaemia

Bone profile: hypophosphataemia/hypocalcaemia

Magnesium: hypomagnesaemia

Other

ECG: deranged electrolytes such as potassium and phosphate can cause fatal arrhythmias

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Myeloma screen

Clinical assessment

Clinical examination:

• Clinical signs of anaemia (e.g. pallor)
• Areas of bony pain

Lab tests

FBC: anaemia/neutropenia/thrombocytopaenia

U&Es: raised creatinine/hypercalcaemia

ESR: raised

Blood film: rouleaux formation (red cells stacked on each other) is typical in myeloma

Protein electrophoresis of blood and urine: raised levels of Bence Jones protein are typical (appearing as a paraprotein band)

Immunoglobulins: measurement of IgG/IgM/IgA can be useful to identify immune paresis.

Imaging

Skeletal survey:

• A series of X-rays of the skull, axial skeleton and proximal long bones to identify the typical lytic lesions associated with multiple myeloma.
• MRI is more sensitive than X-ray at detecting lytic lesions, particularly those in the vertebrae.

Bone marrow biopsy

To assess the percentage of bone marrow occupied by plasma cells (this helps with diagnostic stratification).

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Liver screen

Clinical assessment

Clinical examination:

• Examine the abdomen and assess for stigmata of liver disease

Liver function

LFTs

Coagulation screen

Viruses

Hepatitis serology (A/B/C)

Epstein-Barr Virus (EBV)

Cytomegalovirus (CMV)

Autoimmune antibodies

Anti-mitochondrial antibody (AMA)

Anti-smooth muscle antibody (ASMA)

Anti-liver/kidney microsomal antibodies (Anti-LKM)

Anti-nuclear antibody (ANA)

p-ANCA

Other

Immunoglobulins: IgM/IgG

Alpha-1 Antitrypsin: Alpha-1 antitrypsin deficiency

Serum Copper: Wilson’s disease

Ceruloplasmin: Wilson’s disease

Ferritin: haemochromatosis

Liver biopsy

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