User blogs

The kidneys help remove waste products from the body, maintain balanced electrolyte levels, and regulate blood pressure.

Share on PinterestMoMo Productions/Getty Images

The kidneys are a pair of bean-shaped organs located below the rib cage, one on each side of the spine.

This article looks at the structure and function of the kidneys, the diseases that affect them, and how to keep them healthy.

Trusted Source just below the rib cage, with one on each side of the spine. The right kidney is generally slightly lower than the left kidney to make space for the liver.

Each kidney is approximately 3 centimeters (cm) thick, 6 cm wide, and 12 cm long. Across all sexes and weights, the left kidney is 10 grams (g) heavier than the right kidney.

The kidneys are two bean-shaped organs that are roughly the size of a fist. A tough, fibrous renal capsule surrounds each kidney and provides support for the soft tissue inside. Beyond that, two layers of fat serve as further protection. The adrenal glands lie on top of the kidneys.

Inside the kidneys are a number of pyramid-shaped lobes. Each consists of an outer renal cortex and an inner renal medulla. Nephrons flow between these sections. Each nephron includes a filter, called the glomerulus, and a tubule.

The glomerulus filters blood, which enters the kidneys through the renal arteries and leaves through the renal veins. The kidneys are relatively small organs, but they receive 20% to 25%Trusted Source of the heart’s output.

The tubule returns necessary substances to the blood and removes waste that then becomes urine. The kidneys excrete urine through the ureter, a tube that leads to the bladder.

Share on Pinterest

The main role of the kidneys is to maintain homeostasis. They manage fluid levels, electrolyte balance, and other factors that keep the internal environment of the body consistent and comfortable.

These organs carry out a wide range of bodily functions.

The kidneys removeTrusted Source various waste products and eliminate them in the urine. They filter around 200 quarts (qt) of blood every 24 hours, and about 2 qt leave the body in the form of urine.

Some major compounds that the kidneys remove are:

• urea, which results from the breakdown of proteins
• uric acid from the breakdown of nucleic acids
• drugs and their metabolites

The kidneys reabsorbTrusted Source nutrients from the blood using tubules and transport them to where they will best support health. They also reabsorb other products to help maintain homeostasis. Reabsorbed products include:

• glucose
• amino acids
• bicarbonate
• water
• phosphate
• chloride, sodium, magnesium, and potassium ions

In humans, the range of acceptable pH levels is 7.35 to 7.45Trusted Source. At levels below or above this range, the body enters a state of acidemia or alkalemia, respectively. In these states, proteins and enzymes break down and can no longer function. In extreme cases, this can be fatal.

The kidneys and lungs help keep the body’s pH stable. The lungs achieve this by moderating the concentration of carbon dioxide in the blood. The kidneys manage the pH by reabsorbing and producing bicarbonate from urine, which helps neutralize acids.

The kidneys can retainTrusted Source bicarbonate if the pH is tolerable and release it if acid levels rise. They can produce new bicarbonate by excreting acid.

Osmolality is a measure of the body’s electrolyte-water balance, which is the ratio between fluids and minerals in the body. Dehydration is a primary cause of electrolyte imbalance.

If osmolality rises in the blood plasma, the hypothalamus in the brain responds by passing a message to the pituitary gland. This gland releases antidiuretic hormone (ADH). In response to ADH, the kidney makes several changes, including:

• increasing urine concentration
• increasing water reabsorption
• reopening portions of the collecting duct that water cannot normally enter, allowing water back into the body
• retaining urea in the medulla of the kidney rather than excreting it, as this compound draws in water

The kidneys regulate blood pressure when necessary, but they are responsible for slower adjustments.

They adjust long-term pressure in the arteries by causing changes in the fluid outside of cells. The medical term for this fluid is extracellular fluid. These fluid changes occur after the release of a vasoconstrictor called angiotensin II. Vasoconstrictors are hormones that cause blood vessels to narrow.

These hormones play a role in increasing the kidneys’ absorption of sodium chloride, or salt. This absorption effectively increases the size of the extracellular fluid compartment and raises blood pressure. Anything that alters blood pressure, including excessive alcohol consumption, smoking, and obesity, can damage the kidneysTrusted Source over time.

The kidneys release several important compounds, including:

• Erythropoietin: This controls erythropoiesis, which is the production of red blood cells. The liver also produces erythropoietin, but the kidneys are its main producers in adults.
• Renin: This enzyme helps manage the expansion of arteries and the volumes of blood plasma, lymph, and interstitial fluid. Lymph is a fluid that contains white blood cells, which support immune activity, and interstitial fluid is the main component of extracellular fluid.
• Calcitriol: This is the hormonally active metabolite of vitamin D. It increases both the amount of calcium that the intestines can absorb and the reabsorption of phosphate in the kidney.

A range of diseases can affect the kidneys. Environmental or medical factors may lead to kidney disease, and they can cause functional and structural problems from birth in some people.

In people with diabetic nephropathy, damage occurs to the capillaries of the kidney as a result of long-term diabetes. The symptoms may not become apparent until yearsTrusted Source after the damage starts to develop. They can include:

• fluid buildup
• sleep difficulty
• poor appetite
• upset stomach
• weakness
• difficulty concentrating

Trusted Source

Here is what you need to know about the drug and why it has been so important recently:

Captagon was the brand name of a psychoactive medicine produced in the 1960s by the German company Degussa Pharma Gruppe. It was mainly prescribed as a treatment for attention deficit disorder, narcolepsy and as a central nervous system stimulant.

Captagon tablets contained fenetylline, a synthetic drug of the phenethylamine family to which amphetamine also belongs.

As official production ceased, some of the remaining stocks were smuggled out of Eastern Europe, in particular Bulgaria, to the Middle East.

Eventually, new counterfeit tablets labelled Captagon were produced in the 1990s to early 2000s in Bulgaria, according to a 2018 report by the European Monitoring Centre for Drugs and Drugs Addiction. The drugs were then smuggled out of the country by Balkan and Turkish criminal networks to the Arabian Peninsula.

Strict crackdowns on production by Turkish and Bulgarian authorities, which included the closure of 18 mostly large-scale laboratories involved in amphetamine synthesis, resulted in a drastic reduction in trade from the Balkans.

In 2011, after a brutal government crackdown on anti-Assad protesters, Syria descended into civil war. Internationally isolated and racked by fighting, the country was plunged into an economic crisis.

Although Damascus denies any involvement in the trade, observers say production and smuggling of the drug have brought in billions of dollars for al-Assad, his associates and allies as they looked for an economic lifeline.

According to a New Lines Institute report, the Syrian government uses “local alliance structures with other armed groups such as Hezbollah for technical and logistical support in Captagon production and trafficking”.

This blog is closing now, and our live coverage of the Israel-Hamas conflict is moving here.

Here’s a summary of the latest developments:

• The Rafah border crossing between Gaza and Egypt will reopen for aid deliveries, US secretary of state Antony Blinken has said. Speaking after a meeting with Egyptian President Abdel Fattah al-Sisi, Blinken did not give any specifics about when the crossing would reopen. US media have reported that it will open at 9am for several hours.

• UNRWA, the UN’s agency supporting Palestinian refugees, said on Sunday that Israel’s deadly strikes on Gaza have led to an “unprecedented human catastrophe” as Gaza’s death toll rises to 2,670 with 9,600 injured. Speaking to reporters, Philippe Lazzarini, commissioner general of UNRWA, said: “If we look at the issue of water, we all know water is life and Gaza is running out of water and Gaza is running out of life.”

• Over 1,000 people were missing under the rubble of buildings in Gaza that have been targeted by deadly Israeli airstrikes, the Palestinian civil defence said on Sunday. In a statement, the civil defence team said many others were pulled alive out of the rubble, 24 hours after buildings were struck.

•   

• Gaza health officials have started to store bodies in ice-cream freezer trucks because moving them to hospitals is too risky and cemeteries are running out of space. Videos posted online showed bodies wrapped in white cloth stacked inside the empty trucks.

• Israeli officials said they were restoring limited water supplies to southern Gaza, amid a wider water crisis, after a call between US President Biden and Israeli Prime Minister Benjamin Netanyahu.

• US and Israelis officials are discussing the possibility of a visit to Israel soon by Biden at the invitation of Netanyahu, a source familiar with the matter told Reuters on Sunday. A potential visit by Biden would follow similar visits from other high-ranking US officials including secretary of state Antony Blinken and defense secretary Lloyd Austin. Blinken is due to return to Israel on Monday for a second round of talks with Netanyahu.

• Biden, speaking to CBS, said he is “confident” Israel will act under the rules of war in its conflict with Palestine, and added deploying US troops is not necessary. In an interview with 60 Minutes, Biden said that while he believes Hamas must be eliminated entirely, there must be a path for a Palestinian state. And he cautioned that the threat of terrorism in the United States had increased due to unrest in the Middle East.

• Reserves of fuel at all hospitals across the Gaza Strip are expected to last only about 24 more hours, the United Nations humanitarian office (OCHA) said on Monday. “The shutdown of backup generators would place the lives of thousands of patients at risk,” OCHA said on its website.

• More than 600,000 Gazans have so far moved to the southern part of the Gaza strip near the Egyptian border city of al-Arish, before an expected Israeli ground offensive. International aid workers in Gaza described an unprecedented situation of “humanitarian collapse”.

• The US has warned that the war between Israel and militant group Hamas could escalate, as American warships headed to the area amid growing clashes on the country’s northern border with Lebanon. “There is a risk of an escalation of this conflict, the opening of a second front in the north and, of course, Iran’s involvement,” White House national security adviser Jake Sullivan told CBS.
  US Defense Secretary Lloyd Austin announced deployment of a second aircraft carrier group late on Saturday, calling it a sign of “our resolve to deter any state or non-state actor seeking to escalate this war.”

• Iran’s foreign minister, Hossein Amir-Abdollahian, said the US would suffer “significant damages” if the war in Gaza spills over into a larger conflict, Al Jazeera reported on Sunday. “We have conveyed our message to the Zionist regime through its allies that if they do not cease their atrocities in Gaza, Iran cannot simply remain an observer,” Iranian state media cited Amir-Abdollahian as telling the network.

• UN secretary-general António Guterres called on Hamas to release hostages without conditions and called on Israel to allow for rapid and unimpeded humanitarian aid access to Gaza. “Each one of these two objectives are valid in themselves. They should not become bargaining chips and they must be implemented because it’s the right thing to do,” Guterres said. The Middle East is on the brink of an “abyss”, he said.

• The Venezuelan president, Nicolas Maduro, has said that he spoke by phone to the Palestinian Authority president, Mahmoud Abbas, on Sunday regarding the situation in Gaza. Maduro told Abbas that Venezuela would send 30 tons of humanitarian aid to Gaza in the next few days, Reuters reports.

• Palestinian Authority President Mahmoud Abbas said the actions and policies of Islamist group Hamas do not represent Palestinian people, according to official news agency Wafa, although it later removed direct references to Hamas from its report. In a phone call with Maduro, “the president affirmed his rejection of the killing of civilians on both sides and called for the release of civilians, prisoners and detainees on both sides,” added the news agency.

• Amnesty International has verified six videos of an attack on Salah al-Din road – a supposedly “safe” route for Palestinians feeling Gaza – that killed at least 70 people. It went on to condemn Israel’s forced evacuations of Palestinians from Gaza, saying: “Israel’s order to ‘evacuate’ is NOT compliant w/ [international humanitarian law] & must be rescinded.”

• France has warned Iran “against any escalation or extension of the conflict” between Israel and Hamas, the French presidential office announced on Sunday. During a phone call between the French president, Emmanuel Macron, and his Iranian counterpart, Ebrahim Raisi, Macron warned against any conflict spillover into Lebanon.

• Leaders from the EU’s 27 member states have issued a statement outlining their position on the situation in the Middle East. “The European Union condemns in the strongest possible terms Hamas and its brutal and indiscriminate terrorist attacks across Israel and deeply deplores the loss of lives,” the European Council said.

• In a call with the Vatican, Israel’s foreign ministry said it expected the “Vatican to be more attentive to the suffering to Israelis.” The country’s foreign minister also called for a clear Vatican condemnation of deadly terrorism against Israelis and reiterated Israel’s right to defend itself.