ovemight (fluid deprVation, urine osmolality usually exceeds 600 mOsmo/1 (sp.gr,>1015) in more formal tests,fluid deprivation fOR upto 24 hrs

Normal filtration barrler is impervioua to molecules öf molecular w1 >aboul 60,000 Dall ons. Proteinurla - (a) in glomerular injury. the amount of albumin increases (b) Microalbuminuria helps early detection öf diäbetic nephropalhy (c) Assessing the Selectivity' of filtration. barner by calculating the proportional clearance of a large, molecule, such as IgG (150,000 Dairons) comparad with a small molacule such as albumin (66.500 Daltons) is öf use In children with nepnrotlc syndrome, a setectivity Index <0>1015) in more formal tests,fluid deprivation for upto 24 hrs or injecllon öf antidiuretic hormone (vasopressin tannate) should increasa urlnary osmolality to 750 mOsmol/1 or mare. 2 Urinary acidifcätion - Kdneys most excrete 70-100 mmol of non-volatile acids/day, otheiwise plasma pH falls and urine pH is high pH of urine can be assessed by dipstck A more formal lest is the acid load test Ammonium chloride 100 mg/kg is grven orally over 30-60 minutes (to avoid vomiting) Urine pH and plasma bicarbonate are measured ovar 3 hrs Tha bicarbonate concentrarion should fall below 18mmol/ 1 andurlna pH belcw53 in metabolic acidosis. plasma bicarbonate is already <20mmol/1>

intemal iliac artery is aiiected alone. claudicaiton in gluteus maximus on walking may be the onry Symptom Dlagnostic aigns

SLR öf füll ränge though painful at the extrems Multiradcular- signs in lower Iimbs muscle weakness billateral, unequal and marked 6 Benign spinal tumour - Progressiva increase in symptome Neurological signs more severe and progressive than in disc lesion if radograph shows srosion of bone and induction af epidural anaesthesia does not cause disappearance öf pain for the time being atumour is very prodably present 7 Major lesions in the butlock -such as acute osteomyelitis of ilium or üpper femur. ischio-recatl abscess pointing into buttock, septic gluteal bursitis Straight leg raising and hip flexion both vary painfut (In. sciaica due to dsc lesion nip flexlon is not imited 8 Arthritöis of the hip - Hip movements restricted and pain provokad by passive movemenis Radiograph of pelvis diagnostic 9 Intermittent claudiction when intemal iliac artery is aiiected alone. claudicaiton in gluteus maximus on walking may be the onry Symptom Dlagnostic aigns • Patient fies prone and his hip is axtended pasaively; this cauaes no pain He is then asked to keep the leg extended for a minute, this brings on the claudication spinal claudicatian - Pins and needes in both lower limbs on walking acrtain distance

PRESENCE OF TENDER NQULES - In parasplnal muscles and along iliac crest may be found in sclatica due to inflammation ofmuscular and fascial structures

PRESENCE OF TENDER NQULES - In parasplnal muscles and along iliac crest may be found in sclatica due to inflammation ofmuscular and fascial structures 5 RECTAL EXAMINATION • in older patients. III. lnvesugations - 1 Imaging of spine - (a) Straight X-rays - for deteocting disc narrowing in lumbar spine, or lesion öf sacro-iliac or hip joinl (b) Myelography to localise level of disc pratrusion and to dflferentiate such lesions from tumours (c) Nuclear magnetic resonance imagjng -usetful in assessment öf rool lesion. 2 CSF -may show lncreased protein with normal cellcounl In farge protrude intervertebral disc 3. EMG -may be usad to contirm presence öf denervation in affected muscles 4 Procaine injection test - for diagnosis of fibrositic pain, contaact with needie aggravates local pain and elicits referred pain, procaine suppresses both. and freedom o lag and apina movemenl \s restored Differential Diagnose öl conoBions causing Sciatfca - 1 DQc tesion - Hecunem boufä of Iowar back pain (lumbago) followed by unilateral sciatica, or pain first in calf or thigh or both without any lumbar symptoms SLR limiled Naurological signs absent if small protrusion. present if large displacernent compressing the root severely A huge hemiation may squeeze the root so hard that it becomes anaesthietic from ischemia and tha pain ceases, SLR becomes once again of full ränge al tha same time äs cutaneous analgesiä and loss öl power and rgflexes supervene 2 Spondytolisthesis Signs of disc lesion - together with lumbar deformity When spondylolisthesis causs intrinsic symptoms backache after prolonged standing, or bilateral sciatica X-ray taken with the patient standing dagnostic 3 Attrtion öf disc - Füll approxlmatlon öf the vertebrai bodies following attrition öf dlsc allows posterior longitudnal ligamenr to be unduly long Sciatica caused by standing due to compression causing posterior bulga of the disintegrated disc which is pushad back into position when posterior longirtudinal ligament is taughtened by lying down X-ray - Diminished joint space with marked anterior beaking at the affected level 4. Sacro-iliac arthrits- Altemation öf pain significant. ie.. pain comes in ona buttock and postenor thlgh, then it transfers tself to tha other side Signs of involvement öf 1st and 2nd säcral segments No lumbar signs Pressure on anterior iliac spines provokes pain in tha buttock SLR normal 5 Secondary deposits in spine - Gradually increasing central backacha, tendency to radiate to lower limö. soon to both Marked llmitation of movements at lumbar spine

maximum velocrty and it may be visualized that these molecules are dragging' the olher laminae This dragging force.that is,the force which causes

means the drop of total pressure ofthe blood dueto its passage through the capiHaries ia not great (fig 5. 7 4). In the venous system pressure is very low (fig 5.7 .4) and hence veins belong to the Iow pressure sysiem' In this connection. it should be remembered that our body is able to constrinct. setectively. the artenioles supplying a particular organ. Thus. arteroles supplying the skin undergo selectiver vasospasm (for example. during early phase of muscular exercise this causes ischemia ofthe skin As arterioles supplying the other organs (e .g skeleta muscles) remain unaffected or are even dilated, the blood is diverted to these argans Thus. in this way, the body achieves 'redustributions'of the blood flow Viscosity At the outset, some comrnonly used terms will be evplained Let mn is a tube (fig 5. 7 513) through which water is flowing in such cases, Sir isaac Newton visualized nearly three ceturies ago. that the flowing water may be considered to be consisting öf large number of concentric taminae (Iike the concentrinc laminae of an onion äs in A of fig 5.75 Each lamna or 'shell' is in intimate comaci with its adjacent laminae Wher such a liquid (water in this example) moves the Velocrty profile' of the laminae takes a parabolaid shape (B in fig 5_7 5) The lamina adjacent to the wall of the tuba, does not move at all, where as the velocity Increases more and more äs the lamina in question is more and more near the central longtudinal axis That is, the moiecules in the central longrtudinal axis has the maximum velocrty and it may be visualized that these molecules are dragging' the olher laminae This dragging force.that is,the force which causes the velocrly gradient in the laminae. is called the shearno forte Fig 575 Across sectiona! view of a laminar flow B Longitudinal view Note, tha velocity is
FILE NO .62621004

bfood through the capillarines it was GHL Hagen, a contemporafy of Poisuille who worked furtner with the problem and found out the mathematical expres

tadeed, AC Burton onc e thmarked that. most of the (Hagen-Poiseuille} Jaw is common sense'l Hagen - Poiseuille law is also known. simply. as Poiseuille's (pronounced. Pawazee, -law Jean Leonard Marie Poiseuille was a Paris based physicioan and physicist who., in 1842, grasped the fundamental principles äs descnbed above in connection with his researches on flow of bfood through the capillarines it was GHL Hagen, a contemporafy of Poisuille who worked furtner with the problem and found out the mathematical expres sion It is emphasized, that only, a Newtonan fluid passing ihrough a rigid lube obeys the Hagen Potisuille's law Blood, stnctly epeaking, is not a Newtonian fluid. also blood vesels are not rigid tubes Nevertheless. Hagen Poiseuille's law gives an idea about the major' determing factors of flow Resistance against the fIow As the blood flows onwards, it faces a 'resislance1 againsl the flov- The resistance has to be overcome othe rwise flow will stop However. in ovetcoming resistance, the flowing blood also loses some öf its. energy (wthich it received ftom the heart because öf the ventncutar contraction) This loss of total energy me ans that the lateral pressure is also falling (see Bemoulli's ptinciple. earlier in this chapter As the resistance is,offered by the vascular tree, which lies peripheral to heart. this is also called ths peripheral resistance The interrelationship between the volume of blood fowing per unit time O the resistance, R, the pressure gradient, , in the Hagen • Poiseulie iaw) is given by the expression [The value of R. there fore is. putting values ofO

excretion is followed by surface scanning öf the kidnevs, to determine if renal function iS dvlded equalIy between the kidheys. Radocontrasl agsnl cle

triamtersne, amiloride, spironolactone, probenecld) (d) Hemoconcentration (e.g. diabetas insipidus), Decrease - (a) Incresed GFR (b) Reduced creatinine load (reduced muscle maas, Iiver failure) (c) Hemodilution (e.g. antidiuretic hormone excess). Plasma urea concentration. Normal equal lo or <> 20-25 mmol/1.if >50-60 increaslngly severe symtoms. Normal ratio of plasma. urea 60-80 CAUSES OFHIGH UREA CREATININE RATfIO (>8O due to factor othar than renal failüre) Increased urea generation - (a) High protein diat (b) Upper Gi bleading (c) Cataboilc illness. (d) Coriciostaroid or tetracyclina toxicity increased lubular urea resorption -(a) Dehydration (b) Salt depletion (c) Hypotension Both factors may coexist Radlotsotope matker clearance. 51Cr-EDTA and 1251-lothalamata are excreted entlrely by glomerular flltration The substance is injected l .v. and clearance. determined by measurement öf radioactlvlty in plasma or urlne. The tagt is msto approprlaie for assessment of renal funclion in patiants wrth normal or near normal plasma creatinine Tachnetium dethylamlne penra-acetc acid (DTPA) is injected iv, the rate of excretion is followed by surface scanning öf the kidnaevs, to determine if renal function iS dvlded equalIy between the kidheys. Radocontrasl agsnl clearance. Assessing the btood claarance öf these agents after i.v. injectlon e useful In patilents in whom GFR is changing rapidy (e.g. evolving or recovering acute renal failure) lll Assessment of flltrtion barrier
FILE NO .62621003

process öf glomerular filtration TO measure creatinineclearance. patienr's urine output is collectad for 24-hrs Plasma creatinlne concentrailon

mlnute) The clearance (vöurme/time) can then be calculated by deterrmining the volume öf ptasma which contatains UV/mmol/mlnute öf the sustanca, that is whera P(mmol/1) the plasma concentration to summarlza formula for clearance. Clearancs = GFR it the substance is fraely fillsrad Since the rala of glomerular filtration depends broadly on the number of glomerull (hence nephrons) present, the amount öf renal damage and therefore tne severity öf renal fallure can be assessed by measuring GFR Factors influencing GFK. Increäse - (a) Pre-renal factors - dehydration, hypotension, severe cardiac failure. (b) Renal damaga (c) Urtnary tract obaiructlon (d) Low-proisin diel (e) Drugs - AGE Inhlbliors, NSAIDS Increase-(a) High proteln dievmeal. (b) Eaily diabetes (c) Pregnancy (d) Growth hormone (a) Acrornagaly, (f) Dlumal Variation (increasedin afternoon) Plasnma creatinine and creatinine clearance Creatinine is the moat useful endogenous meiaoolism for cosessing glomeruar function, and is virlually all excrated by the kidneys, mainly by process öf glomerular filtration to measure creatinineclearance. patienr's urine output is collectad for 24-hrs Plasma creatinlne concentrailon (Pcr mmol/1) and urlne creatinine concentratIon (Ucr mmov 1) are measured and the duration of urinecollection and volume collected are recorded Normal creatine clearance is about 120 mvminute (varias with body size) Creatinine Clearänce (mvmin) - Plasma creatinine concentration -Normal por is O O4-011 mmoV1. Factors influencing plasma creatintine concentration - Increase- (a) Raduced GFR (b] Increased creatninea load .(increäsed muscle mass) (c) Reduced tubular creatinine secretion due to drugs (e,g trlmethoptim.