Kidney Function and Orthostatic Hypotension

Orthostatic Hypotension Blood pressure is the strength of blood pushing against arteries’ walls as the heart beats. Adults have a 120/80 mmHg e normal blood pressure. The numerator represents the systolic pressure which is the measure of blood pressure during active heart beats while the denominator represents the diastolic pressure, which is the blood pressure during passive heart beats (Low & Tomalia, 2015). Consistent rise of blood pressure to over 140/90 mmHg results to high blood pressure, medically referred as hypertension which puts an individual on risk of stroke.

On the other hand, low blood pressure medically referred to as hypotension occurs when the blood pressure is below 90/60. On the contrary, a drop in blood pressure to below 90/60 results to an inadequate brain air supply which results in light-headedness or dizziness and fainting. Once the body’s is unable to rapidly bring blood pressure back to normal one suffers from hypotension. Different factors can inhibit the body ability to control blood pressure which causes hypotension.

Although hypotension is prevalent in some individuals, sever hypotension deprives vital body organs oxygen which could result to organ failure (Ricci, Caterina, and Fedorowski 2015). There exists three different types of clinical hypotension: postural/ orthostatic hypotension, neurally mediated hypotension, and severe hypotension. According to Low & Tomalia (2015), orthostatic hypotension (OH) is a common cardiovascular disorder that occurs due to persistent decline of systolic/diastolic blood pressure to a low of 20/10 mm Hg upon a change of body position. Blood pressure is not constant and varies according to body activity.

Abruptly standing yields a decline in blood pressure and once the body is unable to adjust to normal blood pressure fast enough, orthostatic hypotension can occur. This implies that the cardiovascular system is unable to react to abrupt changes appropriately. Although orthostatic hypotension occurs across all ages, the prevalence increases with age with a high of 30% in senior citizens aged above 70 and 5 % among people aged below 50 years. Rivka suffered from orthostatic hypotension.

According to Ricci, Caterina, Fedorowski (2015), neurally mediated hypotension occurs due to a decline in blood pressure associated with prolonged standing. Neurally mediated hypotension is a condition where the brain and heart do not communicate appropriately. A scary and upsetting situation has been identified as a major cause of Neurally Mediated Hypotension. Unlike the Orthostatic hypotension whose prevalence increases with age, Neurally Mediated Hypotension is more likely in children and less likely in adults.

Severe Hypotension is a life-threatening condition and occurs when the blood pressure declines so low to deprive vital organs such as kidney and brain blood to function. Severe hypotension is linked to shock and occurs due to multiple factors such as severe infections, severe blood loss, severe allergic reactions, severe burns or poisoning. Cause of and management of orthostatic hypotension Dehydration has been reported as the supreme cause of orthostatic hypotension. Dehydration occurs due to less intake of fluids, excessive sweating due to physical activity, severe diarrhea, fever, or vomiting.

When the body loses more water than it is taking in, dehydration occurs. Medical conditions such as anemia, heart conditions, infections, central nervous system disorders, endocrine conditions, pulmonary embolism increases the risk of orthostatic hypotension. Low and Tomalia (2015) point out that the treatment and management vary according to the type of hypotension and severity of the symptoms. While the basic first aid entails lying down right away with legs positioned at a level above the heart, persistence of the symptoms demands immediate medical care.

To manage, orthostatic hypotension, the individual is required to rest by lying down and consumption of water and other fluids with sodium and potassium. Since Rivka had engaged in physical activity without rehydration, she suffered from orthostatic hypotension, hence it’s appropriate to have her lay under a shade and take a power drink. Glomerular filtration rate Recognized as the most precise measure, GRF which a measure of kidney function (Schaeffner 2017). The National Kidney Foundation, (2019) defines GRF as the summation of filtration rates of all your functioning nephrons.

According to Schaeffner (2017) the kidney glomeruli filters fluid into Browman’s space. The measure of the filtered fluid per unit of time is the measure of GFR. GFR is determined by the difference between 140 and person age. It’s measured in ml/min and indicates the rate if filtration of plasma. GFR differs across gender with a healthy adult male having a GFR of 130 ml/min, while a healthy young female reporting a GFR of 110 ml/min. A GFR of < 90 ml/min indicates mild kidney failure.

A GFR of < 6 0mls/min implies moderate kidney failure, 30mls/min implies severe kidney failure while GRF below 15mls/min is identified as end-stage kidney failure, and the patient has to undergo dialysis or translation to live. (The National Kidney Foundation , 2019). Schaeffner (2017) states that dehydration causes a fall of glomerular filtration rate. GFR declines with a decrease in blood pressure due to an excessive fluid loss which causes injury to the kidney.

Dehydration causes low blood pressure which in term causes an override of renal autoregulation by the nervous sympathetic nervous system. Overriding of renal autoregulation causes a contraction of the afferent arteriole which in effect causes a decline in GFR. Located in the hilus of the renal glomerulus, the juxtaglomerular apparatus (JGA) comprises the macula densa, the efferent afferent and arterioles, and the mesangium (Feehally, et al., 2019). The JGA regulates the nephrons functionality. Activation of the juxtaglomerular apparatus present in every nephron supports autoregulation of the renal which increases GFR.

Activation of the juxtaglomerular apparatus stimulates the juxtaglomerular cells to release renin contained in the afferent arteriole into the bloodstream. Presence of renin in the bloodstream causes a conversion of inactive angiotensinogen to angiotensin I which is subsequently converted by enzymes into angiotensin II which causes dilation of afferent arteriole and consequently increasing GFR.

Aldosterone and Distal convoluted tubule The distal convoluted tubule (DCT) is part of kidney nephron s[panning 5mm in length in humans is located between the collecting tubule and the loop of Henle and is partially responsible for sodium, potassium, calcium and PH regulation (Subramanya and Ellison 2014). Hormone Aldosterone regulates the levels of sodium and potassium by excretion of potassium and reabsorbing potassium. Consequently, secretion of aldosterone regulates blood pressure and water loss and retention and blood volume. Feehally, et al., (2019) notes that in dehydrated individual,.