Common investigations include blood urea nitrogen (BUN) and electrolytes, liver function tests, urinalysis, and thyroid function tests. Hematological investigations include hematocrit levels, which are usually raised in HG. An ultrasound scan may be needed to know gestational status and to exclude molar or partial molar pregnancy.

Hyperemesis gravidarum is considered a diagnosis of exclusion. HG can be associated with serious problems in the mother or baby, such as Wernicke's encephalopathy, coagulopathy, peripheral neuropathy.

Women experiencing hyperemesis gravidarum often are dehydrated and lose weight despite efforts to eat. The onset of the nausea and vomiting in hyperemesis gravidarum is typically before the twenty-second week of pregnancy.

Acute episodes of cannabinoid hyperemesis typically last for 24–48 hours and the problem often resolves with long term stopping of cannabis use. Improvement can take one to three months to occur.

Relapses are common, and this is thought to be possibly secondary to a lack of education as many people use or increase their use of cannabis due to their symptoms of nausea and vomiting.

The cause of CVS has not been determined; there are no diagnostic tests for CVS. Several other medical conditions, such as cannabinoid hyperemesis syndrome, can mimic the same symptoms, and it is important to rule these out. If all other possible causes have been excluded, a diagnosis of CVS may be appropriate.

Once formal investigations to rule out gastrointestinal or other causes have been conducted, these tests do not need to be repeated in the event of future episodes.

Cannabinoid hyperemesis was first reported in the Adelaide Hills of South Australia in 2004.

There is considerable research into the causes, diagnosis and treatments for FGIDs. Diet, microbiome, genetics, neuromuscular function and immunological response all interact. Heightened mast cell activation has been proposed to be a common factor among FGIDs, contributing to visceral hypersensitivity as well as epithelial, neuromuscular, and motility dysfunction.

Thalidomide was originally developed and prescribed as a cure for morning sickness in West Germany, but its use was discontinued when it was found to cause birth defects. The United States Food and Drug Administration never approved thalidomide for use as a cure for morning sickness.

There are established criteria to aid in diagnosis of CVS; essential criteria are:

1. A history of three or more periods of intense, acute nausea and unremitting vomiting, as well as pain in some cases, lasting hours to days and even weeks or months

2. Intervening symptom-free or reduced-symptom intervals, lasting weeks to months

3. There are repeated cycles of periods (of varying duration) with intense/acute nausea, with or without vomiting, with or without severe pain, followed by periods of reduced symptoms, followed by gradual increase in CVS symptoms until it peaks (peak intensity is generally relative to cycle intensity).

4. There are differences between early-onset CVS (babies & children) and late onset CVS (adult).

5. Exclusion of metabolic, gastrointestinal, or central nervous system structural or biochemical disease, e.g., individuals with specific physical causes (such as intestinal malrotation)

While most pregnant women experience some itch from time to time, itching on the palms and soles without a visible rash, or persisting severe or extensive itch symptoms should be reported to the midwife or obstetrican.

To obtain a diagnosis of ICP, there are two LFT (liver function tests) and Serum bile acid test. The liver function tests (LFTs) is a simple blood test, the results of which should be available by the next day. If the ALT level is elevated, this, plus pruritus of palms and soles, could be considered as potentially diagnostic of ICP but only with elevated bile acid levels (however LFTs are not always elevated in ICP patients). The serum bile acid blood test for ICP is a quantitative measurement of bile salts. The results of this test often take longer to return, but the test is more specific for ICP.

Other problems with the liver that occur in pregnancy should be considered by the treating clinician. These include preeclampsia, the HELLP syndrome, and acute fatty liver of pregnancy. Furthermore, other causes of hepatitis, like hepatitis viruses, cancer and certain medications, should also be considered.

Some studies support the use of ginger, but overall the evidence is limited and inconsistent. Safety concerns have been raised regarding its anticoagulant properties.

Although blood gas sampling is not always essential for the diagnosis of acidosis, a low pH (in either a venous or arterial sample) does support the diagnosis. If the pH is low (under 7.35) and the bicarbonate levels are decreased (<24 mmol/L), metabolic acidemia is present, and metabolic acidosis is presumed. If the patient has other coexisting acid-base disorders, the pH may be low, normal or high in the setting of metabolic acidosis. If a setting of a cause for metabolic acidosis being noted in the patient's history, a low serum bicarbonate indicates metabolic acidosis even without measurement of serum pH.

Other tests relevant in this context are electrolytes (including chloride), glucose, renal function, and a full blood count. Urinalysis can reveal acidity (salicylate poisoning) or alkalinity (renal tubular acidosis type I). In addition, it can show ketones in ketoacidosis.

To distinguish between the main types of metabolic acidosis, a clinical tool called the anion gap is considered very useful. It is calculated by subtracting the sum of the chloride and bicarbonate levels from the sum of the sodium and potassium levels.

As sodium is the main extracellular cation, and chloride and bicarbonate are the main anions, the result should reflect the remaining anions. Normally, this concentration is about 8-16 mmol/L (12±4). An elevated anion gap (i.e. > 16 mmol/L) can indicate particular types of metabolic acidosis, particularly certain poisons, lactate acidosis, and ketoacidosis.

As the differential diagnosis is made, certain other tests may be necessary, including toxicological screening and imaging of the kidneys. It is also important to differentiate between acidosis-induced hyperventilation and asthma; otherwise, treatment could lead to inappropriate bronchodilation.

Upon diagnosis, many providers will prescribe Ursodeoxycholic Acid. While there is no cure for ICP, and no way to guarantee a successful outcome, studies have shown a slightly better fetal and maternal outcome from administration of Ursodeoxycholic Acid, whereas Cholestyramine appears to only relieve itching.

If additional blood tests to check clotting function identify a problem, giving Vitamin K may help avoid the risk of hemorrhage at delivery.

Delivery by 35–37 completed weeks may be important to fetal outcome as a recent study demonstrated that in severe ICP (defined as bile acids greater than 40 umol/L) the risk of stillbirth was 1.5% compared to 0.5% of uncomplicated pregnancies. This risk rose further if bile acids doubled,

Several different problems may lead to the diagnosis, usually by two years of age:

- seizures or other manifestations of severe fasting hypoglycemia

- hepatomegaly with abdominal protuberance

- hyperventilation and apparent respiratory distress due to metabolic acidosis

- episodes of vomiting due to metabolic acidosis, often precipitated by minor illness and accompanied by hypoglycemia

Once the diagnosis is suspected, the multiplicity of clinical and laboratory features usually makes a strong circumstantial case. If hepatomegaly, fasting hypoglycemia, and poor growth are accompanied by lactic acidosis, hyperuricemia, hypertriglyceridemia, and enlarged kidneys by ultrasound, gsd I is the most likely diagnosis. The differential diagnosis list includes glycogenoses types III and VI, fructose 1,6-bisphosphatase deficiency, and a few other conditions (page 5), but none are likely to produce all of the features of GSD I.

The next step is usually a carefully monitored fast. Hypoglycemia often occurs within six hours. A critical blood specimen obtained at the time of hypoglycemia typically reveals a mild metabolic acidosis, high free fatty acids and beta-hydroxybutyrate, very low insulin levels, and high levels of glucagon, cortisol, and growth hormone. Administration of intramuscular or intravenous glucagon (0.25 to 1 mg, depending on age) or epinephrine produces little rise of blood sugar.

The diagnosis is definitively confirmed by liver biopsy with electron microscopy and assay of glucose-6-phosphatase activity in the tissue and/or specific gene testing, available in recent years.

In the fetus, the normal range differs based on which umbilical vessel is sampled (umbilical vein pH is normally 7.25 to 7.45; umbilical artery pH is normally 7.20 to 7.38). In the fetus, the lungs are not used for ventilation. Instead, the placenta performs ventilatory functions (gas exchange). Fetal respiratory acidemia is defined as an umbilical vessel pH of less than 7.20 and an umbilical artery PCO of 66 or higher or umbilical vein PCO of 50 or higher.

Functional gastrointestinal disorders (FGID) include a number of separate idiopathic disorders which affect different parts of the gastrointestinal tract and involve visceral hypersensitivity and impaired gastrointestinal motility.

Metabolic disorder screening can be done in newborns via the following methods:

- Blood test

- Skin test

- Hearing test

A pH under 7.1 is an emergency, due to the risk of cardiac arrhythmias, and may warrant treatment with intravenous bicarbonate. Bicarbonate is given at 50-100 mmol at a time under scrupulous monitoring of the arterial blood gas readings. This intervention, however, has some serious complications in lactic acidosis, and in those cases, should be used with great care.

If the acidosis is particularly severe and/or intoxication may be present, consultation with the nephrology team is considered useful, as dialysis may clear both the intoxication and the acidosis.

Treatment of uncompensated metabolic acidosis is focused upon correcting the underlying problem. When metabolic acidosis is severe and can no longer be compensated for adequately by the lungs, neutralizing the acidosis with infusions of bicarbonate may be required.

Without adequate metabolic treatment, patients with GSD I have died in infancy or childhood of overwhelming hypoglycemia and acidosis. Those who survived were stunted in physical growth and delayed in puberty because of chronically low insulin levels. Mental retardation from recurrent, severe hypoglycemia is considered preventable with appropriate treatment.

Hepatic complications have been serious in some patients. Adenomas of the liver can develop in the second decade or later, with a small chance of later malignant transformation to hepatoma or hepatic carcinomas (detectable by alpha-fetoprotein screening). Several children with advanced hepatic complications have improved after liver transplantation.

Additional problems reported in adolescents and adults with GSD I have included hyperuricemic gout, pancreatitis, and chronic renal failure. Despite hyperlipidemia, atherosclerotic complications are uncommon.

With diagnosis before serious harm occurs, prompt reversal of acidotic episodes, and appropriate long-term treatment, most children will be healthy. With exceptions and qualifications, adult health and life span may also be fairly good, although lack of effective treatment before the mid-1970s means information on long-term efficacy is limited.

It can be diagnosed clinically in the appropriate context, but may be difficult to confirm radiologically using conventional imaging techniques. Changes are more prominent on MRI than on CT, but often take days or weeks after acute symptom onset to develop. Imaging by MRI typically demonstrates areas of hyperintensity on T2-weighted images.

Regurgitation and heartburn in pregnancy are caused by relaxation of the lower esophageal sphincter (LES) and increased transit time in the stomach (normal in pregnancy), as well as by increased intraabdominal pressure, caused by the enlarging uterus.

Regurgitation and heartburn in pregnancy can be at least alleviated by eating multiple small meals a day, avoiding eating within three hours of going to bed, and sitting up straight when eating.

If diet and lifestyle changes are not enough, antacids and alginates may be required to control indigestion, particularly if the symptoms are mild. If these, in turn, are not enough, proton pump inhibitors may be used.

If more severe, it may be diagnosed as gastroesophageal reflux disease (GERD).

Respiratory alkalosis is very rarely life-threatening, though pH level should not be 7.5 or greater. The aim in treatment is to detect the underlying cause. When PaCO2 is adjusted rapidly in individuals with chronic respiratory alkalosis, metabolic acidosis may occur. If the individual is on a mechanical ventilator then preventing hyperventilation is done via monitoring ABG levels.

Constipation is believed to be caused by decreased bowel mobility secondary to elevated progesterone (normal in pregnancy), which can lead to greater absorption of water, but it can also be caused or worsened by iron supplementation. It causes the "smooth muscle" along the walls of the intestines to relax. Thus, making sure that the future mother will absorb as much nutrients from her diet as possible in order to nourish the fetus and herself. As a side effect the feces can get extremely dehydrated and hard to pass. Constipation can decrease as pregnancy progresses, with a rate as high as 39% at 14 weeks of gestation reducing to 20% at 36 weeks in one study at a time when iron supplementation was common.

Dietary modification with more fiber or fiber supplementation. Also, increased PO fluids, stool softeners, bulking agents and eating fruit and fiber enriched foods often help. There is not enough evidence to say how best to treat constipation in pregnancy. Stimulant laxatives may help but also cause diarrhoea and abdominal pain. Fibre supplementation may also help.

A woman experiencing sudden defecation should report this to her practitioner.

Dozens of congenital metabolic diseases are now detectable by newborn screening tests, especially the expanded testing using mass spectrometry. This is an increasingly common way for the diagnosis to be made and sometimes results in earlier treatment and a better outcome. There is a revolutionary Gas chromatography–mass spectrometry-based technology with an integrated analytics system, which has now made it possible to test a newborn for over 100 mm genetic metabolic disorders.

Because of the multiplicity of conditions, many different diagnostic tests are used for screening. An abnormal result is often followed by a subsequent "definitive test" to confirm the suspected diagnosis.

Common screening tests used in the last sixty years:

- Ferric chloride test (turned colors in reaction to various abnormal metabolites in urine)

- Ninhydrin paper chromatography (detected abnormal amino acid patterns)

- Guthrie bacterial inhibition assay (detected a few amino acids in excessive amounts in blood) The dried blood spot can be used for multianalyte testing using Tandem Mass Spectrometry (MS/MS). This given an indication for a disorder. The same has to be further confirmed by enzyme assays, IEX-Ninhydrin, GC/MS or DNA Testing.

- Quantitative measurement of amino acids in plasma and urine

- IEX-Ninhydrin post column derivitization liquid ion-exchange chromatography (detected abnormal amino acid patterns and quantitative analysis)

- Urine organic acid analysis by gas chromatography–mass spectrometry

- Plasma acylcarnitines analysis by mass spectrometry

- Urine purines and pyrimidines analysis by gas chromatography-mass spectrometry

Specific diagnostic tests (or focused screening for a small set of disorders):

- Tissue biopsy or necropsy: liver, muscle, brain, bone marrow

- Skin biopsy and fibroblast cultivation for specific enzyme testing

- Specific DNA testing

A 2015 review reported that even with all these diagnostic tests, there are cases when "biochemical testing, gene sequencing, and enzymatic testing can neither confirm nor rule out an IEM, resulting in the need to rely on the patient's clinical course."

Metabolic disorders can be treatable by nutrition management, especially if detected early. It is important for dieticians to have knowledge of the genotype to therefore create a treatment that will be more effective for the individual.