Investigations
1st investigations to order
clinical diagnosis
Test
Diagnosis is clinical based on history and physical examination alone.
Result
characteristic 'hic' sound; duration and intensity allows differentiation between benign self-limiting hiccups and chronic hiccups
Investigations to consider
FBC
Test
Abnormal findings include leukocytosis in inflammation or infection, and anaemia in malignancy or gastrointestinal haemorrhage.
Result
normal, or abnormal if underlying cause
serum electrolytes
Test
May reveal hyponatraemia, hypocalcaemia, or hypokalaemia.
Electrolyte disturbances can decrease the central inhibition of the hiccup reflex arc, leading to chronic hiccups.
Result
normal, or abnormal if underlying cause
urea
Test
Urea is elevated in uraemia, which is a potential organic cause of chronic hiccups.
Result
normal, or abnormal if underlying cause
C-reactive protein and erythrocyte sedimentation rate
Test
May be elevated in inflammation, infection, or malignancy.
Several inflammatory and malignant conditions can lead to chronic hiccups.
Result
normal, or abnormal if underlying cause
liver function tests
Test
Aspartate aminotransferase and alanine aminotransferase may be elevated in hepatitis, and alkaline phosphatase may be elevated in biliary obstruction.
Hepatitis, cholecystitis, and cholelithiasis are potential organic causes of chronic hiccups.
Result
normal, or abnormal if underlying cause
gamma glutamyl transpeptidase (gamma-GT)
Test
Gamma-GT may be elevated in biliary obstruction and chronic alcoholism.
Hepatitis, cholecystitis, and cholelithiasis are potential organic causes of chronic hiccups.
Result
normal, or abnormal if underlying cause
serum amylase
Test
Elevated in pancreatitis, which is a potential organic cause of chronic hiccups.
Result
normal, or abnormal if underlying cause
toxicology screen
Test
May reveal elevated blood alcohol, or positive drug screening for tetrahydrocannabinol, amfetamines, cocaine, sedatives, tricyclics.
Various toxins, including alcohol and certain illicit drugs, can lead to chronic hiccups.
Result
normal, or abnormal if underlying cause
arterial blood gas
Test
Alkalosis is a potential organic cause of chronic hiccups.
Result
normal, or abnormal if underlying cause
ECG
Test
May reveal evidence of ischaemia, pericarditis, a pacemaker, or electrolyte disturbances.
Myocardial infarction, pericarditis, an aberrant cardiac pacemaker electrode, and electrolyte disturbances (hyponatraemia, hypocalcaemia, or hypokalaemia) are potential organic causes of chronic hiccups.
Result
normal, or abnormal if underlying cause
chest x-ray
Test
May reveal evidence of pulmonary disease, neoplasm, mediastinal lymphadenopathy, cardiac abnormality, or pacemaker.
Diaphragmatic and phrenic nerve irritation leads to chronic hiccups and may result from pericarditis, or from an aberrant cardiac pacemaker electrode. Irritation of the vagus nerve may result from pneumonia, empyema, bronchitis, asthma, pleuritis, aortic aneurysm, tuberculosis, lung cancer, cor pulmonale, and mediastinitis, leading to chronic hiccups.[6][7][8][9]
Result
normal, or abnormal if underlying cause
pulmonary function tests
Test
May reveal an obstructive or restrictive pulmonary disorder.
Several obstructive and restrictive pulmonary conditions, including asthma, pneumonia, pleuritis, and empyema, are potential organic causes of chronic hiccups.
Result
normal, or abnormal if underlying cause
CT abdomen
Test
May reveal evidence of obstruction, perforation, inflammation, abscess, neoplasm, hepatosplenomegaly, or abdominal aortic aneurysm.
Diaphragmatic and phrenic nerve irritation leads to chronic hiccups and may result from several intra-abdominal pathologies including subphrenic abscess, splenomegaly, hepatomegaly, and a hiatus hernia. Irritation of the vagus nerve may result from gastric cancer, duodenal ulcer, pancreatitis, pancreatic cancer, intra-abdominal abscess, bowel obstruction, abdominal aortic aneurysm, cholecystitis, cholelithiasis, ulcerative colitis, Crohn's disease, gastrointestinal haemorrhage, appendicitis, and hepatitis, leading to chronic hiccups.[6][7][8][9]
Result
normal, or abnormal if underlying cause
endoscopy of the upper gastrointestinal tract
Test
May reveal evidence of oesophagitis, oesophageal cancer, duodenal ulcer, or gastritis.
These conditions may cause irritation of the phrenic and vagus nerves, leading to chronic hiccups.
Result
normal, or abnormal if underlying cause
CT or MRI head
Test
May reveal evidence of a space-occupying lesion, inflammation, haemorrhage, or infarction.
Central processes leading to chronic hiccups include structural lesions (intracranial neoplasm, syringomyelia, multiple sclerosis, ventriculo-peritoneal shunt), vascular lesions (intracranial haemorrhage or infarction, arterio-venous malformation, vascular insufficiency), infection (meningitis, encephalitis, neurosyphilis, malaria, herpes zoster), and trauma.[10][11][12]
Result
normal, or abnormal if underlying cause
lumbar puncture
Test
May reveal elevated protein, decreased glucose, leukocytes, bacteria, or xanthochromic liquor.
Meningitis, encephalitis, and intracranial haemorrhage are potential organic causes of chronic hiccups.
Result
normal, or abnormal if underlying cause
otoscopy
Test
May reveal tympanic membrane irritation.
Irritation of the vagus nerve may result from a foreign body irritating the tympanic membrane, leading to chronic hiccups.
Result
normal, or abnormal if underlying cause
pharyngoscopy
Test
May reveal inflammation of the pharyngeal mucosa.
Pharyngitis may cause irritation of the vagus nerve, leading to chronic hiccups.
Result
normal, or abnormal if underlying cause
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