Generally, people only pay attention to the impact of blood sugar and blood lipids on health. In fact, the concentration of many substances in the blood will affect our health, such as phosphorus. If the concentration of phosphorus in the blood is too low, low blood phosphorus will affect bone formation and abnormal white blood cells. Issues such as these cannot be ignored. If you are prone to fatigue, osteoporosis and other problems, it may be a symptom of hypophosphatemia. The following nephrologist Chen Youcheng will share the causes of hypophosphatemia and the treatment methods.
4 causes of hypophosphatemia
Causes of hypophosphatemia can be roughly divided into four categories:
Kidney phosphorus excretion increases intestinal absorption of phosphorus decreases phosphorus transfer from extracellular to intracellular other causes
The first category_increased phosphorus excretion by the kidneys
【1】Hyperparathyroidism
Reason: Parathyroid hormone will promote the increase of phosphorus excretion by the kidneys.
※It is worth noting that the hyperparathyroidism caused by “vitamin D deficiency” and hypophosphatemia not only come from the increase of phosphorus excretion by the kidneys, but also from the decrease of intestinal absorption of phosphorus caused by “decrease in vitamin D concentration”; on the contrary , Hyperparathyroidism caused by “chronic kidney disease” will cause “hyperphosphatemia” because the kidneys cannot excrete phosphorus.
【2】Increased or increased activity of FGF-23
FGF23 is an important role in the regulation of calcium and phosphorus balance in bones, kidneys, and parathyroid glands. The increase or increase in activity of FGF-23 will lead to phosphorus excretion by the kidneys, resulting in some rare clinical symptoms, such as:
X-Linked Hypophosphatemia (XLH)
Autosomal Dominant Hypophosphatemia Rickets (ADHR)
Autosomal Recessive Hypophosphatemia Rickets (ARHR)
Tumor-Induced Osteomalacia (TIO)
The treatment is usually oral phosphorus ions, supplementing the phosphorus lost by the kidneys, or supplementing vitamin D3. If it is caused by a tumor, the tumor will need to be removed with a knife.
【3】Reduction of phosphorus reabsorption in proximal renal tubules
Conditions that reduce the amount of phosphorus reabsorbed by the proximal tubules include:
Hereditary Hypophosphatemic Rickets with Hypercalciuria (HHRH): SLC34A3 mutation derived from autologous recessive inheritance. Oral phosphorus ions can be used to increase blood phosphorus for treatment. Autosomal recessive renal phosphate wasting: It is derived from the mutation of SLC34A1 caused by autosomal recessive inheritance. NHERF1 mutation: It is derived from the protein related to the transport of NHERF1 and Sodium phosphate cotransporter to the cell membrane. KLOTHO mutation: KLOTHO is related to the transport of phosphorus ions in the kidney. When the proximal renal tubules are extensively disabled, they can no longer absorb organic compounds such as phosphorus, calcium, and amino acids. Divided into two categories: genetic type and acquired type.
【4】Sequelae of kidney transplantation
After a kidney transplant, 90% of people will suffer from hypophosphatemia, which is usually mild to moderate, and most often occurs within a week after the transplant, but it may last for months or even years. The causes are:
FGF-23 excess 25(OH)D versus 1,25(OH)2D deficiency after transplantation for persistent hyperparathyroidism Immunosuppressant use
Treatment is phosphorus supplementation, vitamin D supplementation, and treatment of hyperparathyroidism.
【5】Drug-induced hypophosphatemia
Diuretics: Acetazolamide, Loop diuretics, and certain Thiazides with carbonic anhydrase activity such as Metolazone can increase urinary phosphorus excretion. Steroids: Mainly cause hypophosphatemia by reducing intestinal absorption of phosphorus and increasing renal phosphorus excretion. Drugs for cancer treatment Tyrosine kinase inhibitor (TKI): Imatinib (50%), Sorafenib (13%), Nilotinib. Mechanism of action: Inhibit the release of calcium and phosphorus from bones, combined with secondary hyperparathyroidism, increase urinary phosphorus excretion, or cause part of Fanconi’s syndrome. Intravenous iron: increase phosphorus excretion from urine, and inhibit 1α-hydroxylation. Acetaminophen poisoning: may be related to increased excretion of phosphorus in urine. High dose Estrogen (for metastatic prostate cancer).
【6】Other reasons
Upon recovery from acute tubular necrosis and obstructive uropathy, significant loss of phosphorus from urine occurs. Postoperative hypophosphatemia: liver resection, colorectal surgery, aortic bypass surgery, cardiothoracic surgery, etc. can cause hypophosphatemia. Hypophosphatemia after liver resection: related to increased urinary phosphorus excretion.
The second largest category_reduction in intestinal absorption of phosphorus
【1】Malnutrition
Insufficient phosphorus in the diet.
【2】Malabsorption
Most of the phosphorus is absorbed in the duodenum and jejunum of the small intestine. Diseases related to these two small intestines will affect phosphorus absorption. Or use phosphorus chelating agents: such as calcium flakes, aluminum flakes, magnesium, iron, etc., will form complexes with phosphorus, reducing phosphorus absorption.
【3】Vitamin D deficiency or resistance
Common causes are:
Nutritional deficiencies (insufficient dietary intake, or too little sun exposure) Malabsorption Chronic kidney disease Chronic liver disease Abnormal vitamin D synthesis Defective vitamin D receptors
The third major category_transfer of phosphorus from extracellular to intracellular
【1】Acute respiratory alkalosis
In acute respiratory alkalosis, intracellular carbon dioxide will diffuse to the outside of the cell, resulting in an increase in the intracellular pH value, stimulating glycolysis, and then forming phosphorylated carbohydrates, causing the concentration of extracellular phosphorus ions to decrease, resulting in hypophosphatemia .
When respiratory alkalosis is prolonged and severe enough, severe hypophosphatemia may result. Mild hypophosphatemia may also result from increased ventilation after treating an asthma attack and during a panic attack. Hypophosphatemia is common in patients on respirators, especially those who are also receiving glucose supplements.
【2】Refeeding syndrome
The rapid rise in insulin after refeeding causes phosphorus ions to move into and be used by cells. In chronically malnourished patients, rapid refeeding can cause marked hypophosphatemia. Those at high risk for refeeding syndrome include:
People with eating disorders Chronic alcoholics People with Kwashiorkors People with cancer People with diabetes
The treatment method is moderate phosphorus ion concentration (20-30 mmol/L) in parenteral nutrition, which can avoid hypophosphatemia.
【3】Hungry bone syndrome
After surgical resection of the parathyroid gland, the parathyroid hormone drops rapidly, leading to an increase in bone osteogenesis, causing calcium ions in the blood to quickly enter the bone, resulting in hypocalcemia. A small number of people may experience a decrease in blood phosphorus and high blood potassium.
The fourth category_Other reasons
【1】Alcoholism
Alcohol incapacitates the proximal renal tubules to reabsorb phosphorus, resulting in hypophosphatemia. Alcoholics often suffer from acute respiratory alkalosis due to alcohol withdrawal, sepsis, or liver cirrhosis, which in turn leads to hypophosphatemia. In such patients, refeeding or intravenous glucose stimulates the transfer of phosphate ions into the cells, resulting in severe hypophosphatemia.
※Chronic alcoholics with hypophosphatemia have a higher chance of developing rhabdomyolysis.
【2】Diabetic ketoacidosis
In poorly controlled diabetic patients, phosphorus ions are released from the cells and appear in the urine. Glucosuria, ketonuria, acidosis, and osmotic diuresis can all cause increased urinary phosphorus excretion. Although serum phosphate may be normal, systemic phosphorus stores are usually decreased.
※During the treatment of diabetic ketoacidosis, hypophosphatemia often occurs, mainly because insulin treatment will cause cells to absorb phosphorus ions, causing blood phosphorus to drop rapidly. However, we discourage routine phosphate supplementation to prevent hypophosphatemia, as this can lead to severe hypocalcemia. Reduction of systemic phosphorus levels can itself cause insulin resistance, and insulin requirements can be greatly reduced after phosphorus supplementation.
【3】Acute leukemia, Leukemic phase of lymphoma, hematopoietic period after bone marrow stem cell transplantation
In the case of rapid production of these cells, phosphorus ions are used in large quantities, which will cause hypophosphatemia.
【4】Toxic shock syndrome, sepsis
In the case of rapid infusion supplementation, it will reduce the reabsorption of sodium and phosphorus in the proximal tubule, resulting in transient hypophosphatemia
【5】Heat stroke, high fever
Increased phosphorus excretion by the kidneys can result in hypophosphatemia.
Reminders for healing days
Low blood phosphorus can cause many problems such as rickets and bone loss, muscle atrophy, rhabdomyolysis, irregular heartbeat, respiratory failure, weakened white blood cell function, impaired nerve function, etc. When weakness, unsteady gait, easy fracture, heartbeat Abnormal and other problems, it is best to go to the hospital as soon as possible.
Treatment day extension recommendation:What is the reason for the blood test to check the blood calcium is too high or too low? Will you be okay? Hypercalcemia may coexist with osteoporosis!
Have a good chat and heal your healthy life
This article is reproduced from:Dr. Chen Youcheng・Kidney Specialist The original title is:Causes of hypophosphatemia
Image source: Dr. Chen Youcheng, 123RF
2023-08-16 02:32:49
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