Characteristic symptoms are:

- Sudden penetrating pain in the legs, lower back or abdomen

- Confusion, psychosis, slurred speech

- Severe lethargy

- Convulsions

- Fever

- Hyperkalemia (elevated potassium level in the blood)

- Hypercalcemia (elevated calcium level in the blood): the cause of hypercalcemia is a combination of increased calcium input into the extracellular space and reduced calcium removal by the kidney, this last caused by decreased glomerular filtration and increased tubular calcium reabsorption. Both renal factors are secondary to volume depletion and, in fact, improve rapidly during rehydration with saline infusion.

- Hypoglycemia (reduced level of blood glucose)

- Hyponatremia (low sodium level in the blood)

- Hypotension (low blood pressure)

- Hypothyroid (low T4 level)

- Severe vomiting and diarrhea, resulting in dehydration

- Syncope (loss of consciousness and ability to stand)

Abnormal heart rhythms and asystole are possible complications of hypermagnesemia related to the heart. Magnesium acts as a physiologic calcium blocker, which results in electrical conduction abnormalities within the heart.

Clinical consequences related to serum concentration:

- 4.0 mEq/l decreased reflexes

- >5.0 mEq/l Prolonged atrioventricular conduction

- >10.0 mEq/l Complete heart block

- >13.0 mEq/l Cardiac arrest

Note that the therapeutic range for the prevention of the pre-eclampsic uterine contractions is: 4.0-7.0 mEq/L. As per Lu and Nightingale, serum Mg concentrations associated with maternal toxicity (also neonate depression - hypotonia and low Apgar scores) are:

- 7.0-10.0 mEq/L - loss of patellar reflex

- 10.0-13.0 mEq/L - respiratory depression

- 15.0-25.0 mEq/L - altered atrioventricular conduction and (further) complete heart block

- >25.0 mEq/L - cardiac arrest

Results from a longitudinal study with end-stage renal disease suggest that hypermagnesemia may retard the development of arterial calcifications in end-stage renal disease. Significantly lower values of carotid intima-media thickness and aortic pulse wave velocity values, which are surrogate markers for vascular calcification, were observed in chronic kidney disease patients with high serum magnesium levels (0.90–1.32 mmol/L or 2.18–3.21 mg/dL) indicating a lower arteriosclerotic burden associated with a lower risk of cardiovascular events and mortality. Consequently, people with CKD with mildly elevated magnesium levels could have a survival advantage over those with lower magnesium levels.

Adrenal crisis is caused by a deficiency of cortisol resulting from Addison's disease, congenital adrenal hyperplasia (CAH), corticosteroid biosynthetic enzyme defects or pituitary disorders (such as Sheehan's syndrome, pituitary adenoma, hypopituitarism (inactive or underactive pituitary) causing failure to activate the adrenal glands.

The symptoms of an elevated potassium level are nonspecific, and generally include malaise, palpitations, and muscle weakness. Hyperventilation may indicate a compensatory response to metabolic acidosis, which is one of the possible causes of hyperkalemia. Often, however, the problem is detected during screening blood tests for a medical disorder, or after hospitalization for complications such as cardiac arrhythmia or sudden cardiac death. High levels of potassium (> 5.5 mmol/L) have been associated with cardiovascular events.

Physicians taking a medical history may focus on kidney disease, medication use (e.g. potassium-sparing diuretics), which are common causes.

Glycerol Kinase Deficiency causes the condition known as hyperglycerolemia, an accumulation of glycerol in the blood and urine. This excess of glycerol in bodily fluids can lead to many more potentially dangerous symptoms. Common symptoms include vomiting and lethargy. These tend to be the only symptoms, if any, present in adult GKD which has been found to present with fewer symptoms than infant or juvenile GKD. When GKD is accompanied by Duchenne Muscular Dystrophy and Adrenal Hypoplasia Congenita, also caused by mutations on the Xp21 chromosome, the symptoms can become much more severe. Symptoms visible at or shortly after birth include:

- cryptorchidism

- strabismus

- seizures

Some other symptoms that become more noticeable with time would be:

- metabolic acidosis

- hypoglycemia

- adrenal cortex insufficiency

- learning disabilities

- osteoporosis

- myopathy

Many of the physically visible symptoms, such as cryptorchidism, strabismus, learning disabilities, and myopathy, tend to have an added psychological effect on the subject due to the fact that they can set him or her apart from those without GKD. Cryptorchidism, the failure of one or both of the testes to descend to the scrotum, has been known to lead to sexual identity confusion amongst young boys because it is such a major physiological anomaly. Strabismus is the misalignment of one’s eyes. Typically, one is focused but the other is “lazy” and is directed inward or out ward (up and down is less common but does occur).

Signs and symptoms of hyponatremia include nausea and vomiting, headache, short-term memory loss, confusion, lethargy, fatigue, loss of appetite, irritability, muscle weakness, spasms or cramps, seizures, and decreased consciousness or coma. The presence and severity of signs and symptoms are related to the level of salt in the blood, with lower levels of plasma sodium associated with more severe symptoms. However, emerging data suggest that mild hyponatremia (plasma sodium levels at 131–135 mmol/L) is associated with numerous complications or subtle, presently unrecognized symptoms (for example, increased falls, altered posture and gait, reduced attention).

Neurological symptoms typically occur with very low levels of plasma sodium (usually <115 mmol/L). When sodium levels in the blood become very low, water enters the brain cells and causes them to swell. This results in increased pressure in the skull and causes "hyponatremic encephalopathy". As pressure increases in the skull, herniation of the brain can occur, which is a squeezing of the brain across the internal structures of the skull. This can lead to headache, nausea, vomiting, confusion, seizures, brain stem compression and respiratory arrest, and non-cardiogenic accumulation of fluid in the lungs. This is usually fatal if not immediately treated.

Symptom severity depends on how fast and how severe the drop in blood salt level. A gradual drop, even to very low levels, may be tolerated well if it occurs over several days or weeks, because of neuronal adaptation. The presence of underlying neurological disease such as a seizure disorder or non-neurological metabolic abnormalities, also affects the severity of neurologic symptoms.

Chronic hyponatremia can lead to such complications as neurological impairments. These neurological impairments most often affect gait (walking) and attention, and can lead to increased reaction time and falls. Hyponatremia, by interfering with bone metabolism, has been linked with a doubled risk of osteoporosis and an increased risk of bone fracture.

Hyperkalemia, also spelled hyperkalaemia, is an elevated level of potassium (K) in the blood serum. Normal potassium levels are between 3.5 and 5.0 mmol/L (3.5 and 5.0 mEq/L) with levels above 5.5 mmol/L defined as hyperkalemia. Typically this results in no symptoms. Occasionally when severe it results in palpitations, muscle pain, muscle weakness, or numbness. An abnormal heart rate can occur which can result in cardiac arrest and death.

Common causes include kidney failure, hypoaldosteronism, and rhabdomyolysis. A number of medications can also cause high blood potassium including spironolactone, NSAIDs, and angiotensin converting enzyme inhibitors. The severity is divided into mild (5.5-5.9 mmol/L), moderate (6.0-6.4 mmol/L), and severe (>6.5 mmol/L). High levels can also be detected on an electrocardiogram (ECG). Pseudohyperkalemia, due to breakdown of cells during or after taking the blood sample, should be ruled out.

Initial treatment in those with ECG changes is calcium gluconate. Medications that might worsen the condition should be stopped and a low potassium diet should be recommended. Other medications used include dextrose with insulin, salbutamol, and sodium bicarbonate. Measures to remove potassium from the body include furosemide, polystyrene sulfonate, and hemodialysis. Hemodialysis is the most effective method. The use of polystyrene sulfonate, while common, is poorly supported by evidence.

Hyperkalemia is rare among those who are otherwise healthy. Among those who are in hospital, rates are between 1% and 2.5%. It increases the overall risk of death by at least ten times. The word "hyperkalemia" is from "hyper-" meaning high; "kalium" meaning potassium; and "-emia", meaning "in the blood".

Elevated alkaline phosphatase describes the situation where the levels of alkaline phosphatase (ALP) exceed the reference range. This group of enzymes has a low substrate specificity and catalyzes the hydrolysis of phosphate esters in a basic environment. The major function of alkaline phosphatase is transporting across cell membranes. Alkaline phosphatases are present in many human tissues, including bone, intestine, kidney, liver, placenta and white blood cells. Damage to these tissues causes the release of ALP into the bloodstream. Elevated levels can be detected through a blood test. Elevated alkaline phosphate is associated with certain medical conditions or syndromes (e.g., hyperphosphatasia with mental retardation syndrome, HPMRS). It serves as a significant indication for certain medical conditions, diseases and syndromes.

If the reason for alkaline phosphatase is unknown, isoenzyme studies using electrophoresis can confirm the source of the ALP. Heat stability also distinguishes bone and liver isoenzymes ("bone burns, liver lasts").

The specific causes of hyponatremia are generally divided into those with low tonicity (lower than normal concentration of solutes), without low tonicity, and falsely low sodiums. Those with low tonicity are then grouped by whether the person has high fluid volume, normal fluid volume, or low fluid volume. Too little sodium in the diet alone is very rarely the cause of hyponatremia.

Hypophosphatemia is diagnosed by measuring the concentration of phosphate in the blood. Concentrations of phosphate less than 0.81 mmol/L (2.5 mg/dL) are considered diagnostic of hypophosphatemia, though additional tests may be needed to identify the underlying cause of the disorder.

Primary hypophosphatemia is the most common cause of nonnutritional rickets. Laboratory findings include low-normal serum calcium, moderately low serum phosphate, elevated serum alkaline phosphatase, and low serum 1,25 dihydroxy-vitamin D levels, hyperphosphaturia, and no evidence of hyperparathyroidism.

Other rarer causes include:

- Certain blood cancers such as lymphoma or leukemia

- Hereditary causes

- Liver failure

- Tumor-induced osteomalacia

Other unlisted musculoskeletal conditions may also cause elevated alkaline phosphatase.

Metastatic calcification is deposition of calcium salts in otherwise normal tissue, because of elevated serum levels of calcium, which can occur because of deranged metabolism as well as increased absorption or decreased excretion of calcium and related minerals, as seen in hyperparathyroidism.

In contrast, dystrophic calcification is caused by abnormalities or degeneration of tissues resulting in mineral deposition, though blood levels of calcium remain normal. These differences in pathology also mean that metastatic calcification is often found in many tissues throughout a person or animal, whereas dystrophic calcification is localized.

Metastatic calcification can occur widely throughout the body but principally affects the interstitial tissues of the vasculature, kidneys, lungs, and gastric mucosa. For the latter three, acid secretions or rapid changes in pH levels contribute to the formation of salts.

Children with Liddle syndrome are frequently asymptomatic. The first indication of the syndrome often is the incidental finding of hypertension during a routine physical exam. Because this syndrome is rare, it may only be considered by the treating physician after the child's hypertension does not respond to medications for lowering blood pressure.

Adults could present with nonspecific symptoms of low blood potassium, which can include weakness, fatigue, palpitations or muscular weakness (shortness of breath, constipation/abdominal distention or exercise intolerance). Additionally, long-standing hypertension could become symptomatic.

Adult patients have worsening myalgias, bone pains and fatigue which are followed by recurrent fractures. Children present with difficulty in walking, stunted growth and deformities of the skeleton (features of rickets).

Liddle's syndrome, also called Liddle syndrome is a genetic disorder inherited in an autosomal dominant manner that is characterized by early, and frequently severe, high blood pressure associated with low plasma renin activity, metabolic alkalosis, low blood potassium, and normal to low levels of aldosterone. Liddle syndrome involves abnormal kidney function, with excess reabsorption of sodium and loss of potassium from the renal tubule, and is treated with a combination of low sodium diet and potassium-sparing diuretic drugs (e.g. amiloride). It is extremely rare, with fewer than 30 pedigrees or isolated cases having been reported worldwide as of 2008.

Presenting in infancy, symptoms include lack of appetite, vomiting, dehydration, hypotonia and failure to thrive.

Most cases of familial hypocalciuric hypercalcemia are asymptomatic. Laboratory signs of FHH include:

- Hypercalcemia

- Hypocalciuria ( Ca excretion rate < 0.02 mmol/L)

- Hypermagnesemia

- High normal to mildly elevated parathyroid hormone

Oncogenic osteomalacia or tumor-induced osteomalacia, also known as oncogenic hypophosphatemic osteomalacia or oncogenic osteomalacia, is an uncommon disorder resulting in increased renal phosphate excretion, hypophosphatemia and osteomalacia. It may be caused by a phosphaturic mesenchymal tumor.

Urocanic aciduria is thought to be relatively benign. Although aggressive behavior and mental retardation have been reported with the disorder, no definitive neurometabolic connection has yet been established.

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by excessive unsuppressible release of antidiuretic hormone (ADH) either from the posterior pituitary gland, or an abnormal non-pituitary source. Unsuppressed ADH causes an unrelenting increase in solute-free water being returned by the tubules of the kidney to the venous circulation.

ADH is derived from a preprohormone precursor that is synthesized in cells in the hypothalamus and stored in vesicles in the posterior pituitary. "Appropriate" ADH secretion is regulated by osmoreceptors on the hypothalamic cells that synthesize and store ADH: plasma hypertonicity activates these receptors, ADH is released into the blood stream, the kidney increases solute-free water return to the circulation, and the hypertonicity is alleviated. "Inappropriate" ADH secretion causes a "unrelenting increase" in solute-free water ("free water") absorption by the kidneys, with two consequences. First, in the extracellular fluid (ECF) space, there is a dilution of blood solutes, causing hypoosmolality, including a low sodium concentration - hyponatremia. Then virtually simultaneously, in the intracellular space, cells swell, i.e. intracellular volume increases. Swelling of brain cells causes various neurological abnormalities which in severe or acute cases can result in convulsions, coma, and death.

The causes of SIADH are grouped into six categories: 1) central nervous system diseases that directly stimulate the hypothalamus, the site of control of ADH secretion; 2) various cancers that synthesize and secrete ectopic ADH; 3) various pulmonary diseases; 4) numerous (at least seventeen) drugs that chemically stimulate the hypothalamus; 5) inherited mutations that cause aquaporins always to be "turned on"; and 6) miscellaneous largely transient conditions.

Potential treatments of SIADH include restriction of fluid intake, correction of an identifiable reversible underlying cause, and/or medication which promotes solute-free water excretion by the kidney. The presence of cerebral edema may necessitate intravenous isotonic or hypertonic saline administration.

SIADH was originally described in 1957 in two people with small-cell carcinoma of the lung.

Familial hypocalciuric hypercalcemia (FHH) is a condition that can cause hypercalcemia, a serum calcium level typically above 10.2 mg/dL. It is also known as familial benign hypocalciuric hypercalcemia (FBHH) where there is usually a family history of hypercalcemia which is mild, a urine calcium to creatinine ratio <0.01, and urine calcium <200 mg/day.

Antidiuretic hormone (ADH) is released from the posterior pituitary for a number of physiologic reasons. The majority of people with hyponatremia, other than those with excessive water intake (polydipsia) or renal salt wasting, will have elevated ADH as the cause of their hyponatremia. However, not every person with hyponatremia and elevated ADH has SIADH. One approach to a diagnosis is to divide ADH release into appropriate (not SIADH) or inappropriate (SIADH).

Appropriate ADH release can be a result of hypovolemia, a so-called osmotic trigger of ADH release. This may be true hypovolemia, as a result of dehydration with fluid losses replaced by free water. It can also be perceived hypovolemia, as in the conditions of congestive heart failure (CHF) and cirrhosis in which the kidneys perceive a lack of intravascular volume. The hyponatremia caused by appropriate ADH release (from the kidneys' perspective) in both CHF and cirrhosis have been shown to be an independent poor prognostic indicator of mortality.

Appropriate ADH release can also be a result of non-osmotic triggers. Symptoms such as nausea/vomiting and pain are significant causes of ADH release. The combination of osmotic and non-osmotic triggers of ADH release can adequately explain the hyponatremia in the majority of people who are hospitalized with acute illness and are found to have mild to moderate hyponatremia. SIADH is less common than appropriate release of ADH. While it should be considered in a differential, other causes should be considered as well.

Cerebral salt wasting syndrome (CSWS) also presents with hyponatremia, there are signs of dehydration for which reason the management is diametrically opposed to SIADH. Importantly CSWS can be associated with subarachnoid hemorrhage (SAH) which may require fluid supplementation rather than restriction to prevent brain damage.

Most cases of hyponatremia in children are caused by appropriate secretion of antidiuretic hormone rather than SIADH or another cause.

Haemochromatosis is in its manifestations, "i.e.", often presenting with signs or symptoms suggestive of other diagnoses that affect specific organ systems. Many of the signs and symptoms below are uncommon and most patients with the hereditary form of haemochromatosis do not show any overt signs of disease nor do they suffer premature morbidity.

The classic triad of cirrhosis, bronze skin and diabetes is not as common any more because of earlier diagnosis.

The more common clinical manifestations include:

- Fatigue

- Malaise

- Joint and bone pain

- Liver cirrhosis (with an increased risk of hepatocellular carcinoma) Liver disease is always preceded by evidence of liver dysfunction including elevated serum enzymes specific to the liver, clubbing of the fingers, leuconychia, asterixis, hepatomegaly, palmar erythema and spider naevi. Cirrhosis can also present with jaundice (yellowing of the skin) and ascites.

- Insulin resistance (often patients have already been diagnosed with diabetes mellitus type 2) due to pancreatic damage from iron deposition

- Erectile dysfunction and hypogonadism, resulting in decreased libido

- Congestive heart failure, abnormal heart rhythms or pericarditis

- Arthritis of the hands (especially the second and third MCP joints), but also the knee and shoulder joints

- Damage to the adrenal gland, leading to adrenal insufficiency

Less common findings including:

- Deafness

- Dyskinesias, including Parkinsonian symptoms

- Dysfunction of certain endocrine organs:

- Parathyroid gland (leading to hypocalcaemia)

- Pituitary gland

- More commonly a slate-grey or less commonly darkish colour to the skin (see pigmentation, hence its name "diabetes bronze" when it was first described by Armand Trousseau in 1865)

- An increased susceptibility to certain infectious diseases caused by siderophilic microorganisms:

- "Vibrio vulnificus" infections from eating seafood or wound infection

- "Listeria monocytogenes"

- "Yersinia enterocolica"

- "Salmonella enterica" (serotype Typhymurium)

- "Klebsiella pneumoniae"

- "Escherichia coli"

- "Rhizopus arrhizus"

- "Mucor" species

Males are usually diagnosed after their forties and fifties, and women several decades later, owing to regular iron loss through menstruation (which ceases in menopause). The severity of clinical disease in the hereditary form varies considerably. There is evidence suggesting that hereditary haemochromatosis patients affected with other liver ailments such as hepatitis or alcoholic liver disease suffer worse liver disease than those with either condition alone. There are also juvenile forms of hereditary haemochromatosis that present in childhood with the same consequences of iron overload.