Lungs and Kidneys work in an orchestrated manner to maintain an appropriate level of oxygen in blood. Both organs receive all blood flow at one point. Lungs receive blood to facilitate gas exchange: CO2 released and oxygen caught from air. Kidneys filtrate the blood to clear from many residues of metabolism. Given these circumstances, these organs are perfect to carry on with all the blood during its circulation.
Filtering but controlling what’s being filtered
However, what about if lungs fail to catch oxygen and this gas is reduced in blood. Which organ should control the signal? If this task is deferred to the brain the consequences may be deleterious for the entire body. Then, the best option is to give this duty to kidneys.
The kidney’s erithropoyetin
When kidneys sense that the blood being filtered is lacking oxygen, they cooperate recommending the creation of more red cells with enough Hemoglobin (Hb) to catch up oxygen from lungs. The renal cooperation is provided with an hormone called erithropoyetin which works at the bone marrow to induce the formation of red blood cells (RBC) that may be able to take oxygen and bring it to the tissues.
Erithocytosis: increased red blood cells
This situation may take some time (when kidneys consider that the lack of oxygen seems to be serious). The resultant condition is an increased level of RBC with high levels of Hb. This effect is called erithrocytosis, erithremia, polyglobulia, secondary polycytemia, and so forth. Blood turns into thick and slow during its circulation leading to some dizziness and headaches.
Cardiovascular effect of erithrocytosis
With this type of blood, the heart needs to work harder: how to push this heavy luggage? The condition may generate a bigger heart in terms of walls with less space to fill.
Lung diseases as responsible of erithrocytosis
Many lung illnesses are signaled by the presence of secondary erithrocytosis due to difficulties in allowing the access of oxygen to the blood. Advanced stages of COPD are presented with high levels of Hb and RBC and this indicates distant complications from the lungs. The Chronic Bronchitis phenotype (constant cough and sputum production) is classically accompanied with erithrocytosis and increased Hb.
Not a healthy feature
The key fact is that secondary erithrocytosis with high Hb is not a healthy feature when they are seen in an adequate context. COPD and its eventual lung decrease in oxygen catch leads to kidney to send signals that create a huge confusion in the body with a consequence as the one described.
It’s good to assess oxygen levels and blood samples to evaluate further the lung and kidney cooperation in many pulmonary diseases. And this is just one of several joined efforts of lungs and kidneys preserving our corporal functions.