Low Uric Acid

Generality

Low uric acid indicates a reduced concentration of this metabolite in the blood or urine. Through the dosage of this compound it is possible to diagnose, monitor or prevent some diseases that may depend on the scarce capacity of our body to eliminate it correctly.

In particular, reduced values of uric acid compared to the norm can be indicative of pathologies of the liver or kidney . Among the main causes of this finding are also lactic acidosis, fasting, chronic alcohol abuse and blood disorders, such as anemia. Low uric acid may also depend on hereditary metabolic defects, exposure to toxic substances and drug therapies.

In any case, the result must be supported by other tests and must be interpreted within a complete clinical picture.

Uric acid: brief introduction

Uric acid is the terminal product of purine degradation (adenine and guanine). The latter are nitrogenous bases that constitute elements of our body, such as the DNA present in the cell nucleus. Most purines come from endogenous synthesis (that is, through normal cell turnover), while only a minimal percentage derives from foods introduced with the diet (such as liver, anchovies, mackerel, peas and dried beans).
Uric acid circulates in the blood, partly free and partly linked to transport proteins. The organ responsible for its removal from the body is the kidney, which, through its particular filter action, regulates the excretion of the metabolite with urine ; to a lesser extent, uric acid is excreted in the faeces.
Uricemia is the parameter that expresses the amount of uric acid present in the bloodstream. High levels of the metabolite in the blood are defined as " hyperuricemia ", while concentrations lower than normal are called " hypouricemia ".

What's this

Uric acid is a substance that is physiologically produced by our body. This represents, in particular, a waste product that is filtered by the kidneys and eliminated through urine and faeces. Its concentration in the blood (uricemia) is the result of the balance between its production by the body and its excretion.

Uric acid is one of the most common indicators of kidney function, more or less efficient. When the levels of this metabolite in the blood are too low, ie they are below normal values, we are dealing with a hypouricemia.

This condition is found quite rarely and is usually less worrying than hyperuricemia (high blood uric acid due to excess production and / or difficult renal excretion).

Why do you measure

Uric acid testing is used to detect or monitor levels of this metabolite. The dosage can be performed by taking a blood sample (fasted) or in the 24-hour urine .

The purpose of this assessment consists mainly of:

Confirm the suspicion of low levels compared to the norm;
Monitor uric acid values over time, during certain drug therapies.

Any alterations with respect to normal values could be the subject of further investigation by the doctor, in order to identify the causes of low uric acid. This diagnostic path is useful for establishing the most appropriate therapy to restore a normal situation.

Normal values

The normal values of uric acid in the blood range from 4 to 8 mg / dl (milligrams per deciliter).

The concentrations of the metabolite vary with age and sex and, as with any other type of test to assess blood parameters, it is good to remember that each laboratory can have a reference range. If the value resulting from the analysis is lower than the values reported in the report, it means that uric acid is low.

Generally speaking, however, we can speak of low uric acid when the values are less than 4 mg / dl .

Low uric acid - Causes

The main causes of low uric acid are essentially two:

Reduced production of uric acids;
Increased renal or intestinal urate elimination.

These conditions can be found in numerous problems. First of all, a decrease in the metabolite in the blood and urine may depend on an altered renal function, transient or chronic. Therefore, low uric acid can be observed in the context of any pathological process affecting the kidneys ( nephropathies ). These conditions include Fanconi syndrome (characterized by multiple defects in proximal tubular reabsorption).

More simply, the reduced quantity of the metabolite can result from fasting or from a low intake of animal proteins and purines deriving from foods such as liver, kidneys, anchovies and sardines. Reduced levels of the metabolite in the urine can also be observed in the case of chronic alcohol abuse .

Hypouricemia, or the low concentration of uric acid in the blood, is also found in blood disorders, such as anemia, multiple myeloma and Hodgkin's lymphoma. Metabolite values may also decrease during certain liver diseases, such as viral hepatitis.

Low uric acid can also result from lactic acidosis, a metabolic decompensation that causes an accumulation of acids in tissues and body fluids.

Reduced values of the metabolite can be caused by exposure to toxic substances. Other times, low uric acid depends on some forms of cancer or hereditary metabolic defects, such as Wilson's disease (a condition characterized by a systemic accumulation of copper in different tissues of the body, including liver and central nervous system ).

A lowering of blood uric acid levels could be associated with several other pathological conditions, including: celiac disease, acromegaly, syndrome of inappropriate ADH (SIADH) and xanthinuria secretion (purine dysmetabolism due to enzyme xanthine dehydrogenase / oxidase deficiency ).

Another cause of low uric acid are some pharmacological therapies that have the effect of inhibiting the tubular reabsorption of the metabolite at kidney level. In particular, low concentrations are found during treatments based on estrogens and cortisone. The intake of aspirin or other high-dose salicylates also reduces the concentration of uric acid; these drugs can be used to treat, for example, rheumatoid arthritis. Other medicines that can induce this effect are probenecid, sulfinpyrazone, allopurinol and dicumarolics.

Even during pregnancy the values of uric acid can be low: this represents a condition of absolute normality; similarly, low creatinine levels and elevated fibrinogen levels are found.

High uric acid - Causes and possible consequences

If uric acid is produced in excess or is not sufficiently eliminated by the kidneys, it can accumulate in the body. The increased synthesis of the metabolite can be found in case of increased cell death (as happens when you are undergoing some chemotherapy or radiotherapy treatments for cancer). The reduced excretion of uric acid is, instead, the result of impaired renal function.

The higher the level and duration of hyperuricemia, the greater the likelihood of developing gout . This latter condition is characterized by painful inflammation of the joints, associated with the precipitation of uric acid in the form of needle-like crystals of monosodium urate within the synovial fluid.

When it accumulates in the urine without being able to dissolve, then, uric acid remains in the urinary tract. Here it can precipitate in the form of small crystals of flattened or sometimes irregular shape, which can be aggregated in grains or calculations. These elements can cause obstructive uropathy, as well as predict the onset of kidney disease .

How to measure it

The dosage of uricemia occurs after blood is drawn from a vein in the forearm. If necessary, the person must carry a container with the urine collected within 24 hours, in order to be able to evaluate the uricosuria, that is the evaluation of the quantity of uric acid present in the urine.

Preparation

The uricemia dosage requires that the patient is fasting for at least 8-10 hours before taking, but it is possible to drink small amounts of water. Before the exam, it is advisable to remain upright for at least 30 minutes.

Interpretation of Results

Low levels of uric acid in the blood are found less often than in hyperuricemia. In any case, this result must be examined in more detail by specific examinations.

The symptoms that can be found in the presence of low uric acid depend strictly on the cause from which the decrease is caused. However, in the most significant forms we can manifest:

Nausea;
Energy loss;
Mild fever;
Loss of appetite.

The main cause of a reduction in the levels of uric acid in the blood is an inadequate diet (fasting or a diet low in foods rich in purines, such as meat).

A decrease in the concentration of the metabolite in the blood may depend on impaired renal function (acute or chronic nephropathy). Hypouricemia, ie the low concentration of uric acid in the blood, is also found in Wilson's disease (hereditary metabolic defect) and in blood disorders.

Low values can be associated with some liver diseases (especially during viral hepatitis), Fanconi syndrome or exposure to toxic substances.

The levels of uricemia decrease during therapies with various drugs, including cortisone, estrogen and high-dose salicylates.

Low uric acid in the urine can be observed especially in chronic alcoholism.